10. Producing Static Charge

5A10.01 peizoelectricity see 5E60.20
5A10.10 rods, fur, and silk PVC rod and felt, acrylic rod and cellophane, with the Braun electroscope as a charge indicator
5A10.10 rods, fur, silk PVC rod and felt, acrylic rod and cellophane, Braun electroscope, electrophorus.
5A10.10 electrostatic charges Rods, fur, etc.
5A10.10 electrostatic rods Rub acrylic and rubber rods with wool and place on a pivot. Graphic overlays show charges.
5A10.11 separating charge Several common ways to separate charges. Scuff a rug and then discharge through a neon bulb.
5A10.12 charge the student Strike a student sitting on an insulated stool on the back with a fur. If the student holds a key, sparks may be drawn without discomfort.
5A10.15 triboelectric series
5A10.15 triboelectric series, halos A triboelectric series including modern polymers is listed to help in finding a way to charge yourself so you can levitate a thin metalized plastic hoop as a halo.
5A10.15 triboelectric series A list of items sorted according to polarity of charge produced by rubbing.
5A10.16 identifying charges Use an electroscope charged with known sign to test other charged objects.
5A10.17 electrification by rubbing Some electrification by rubbing results that are not easily explained by the close contact theory.
5A10.20 electrophorus
5A10.20 electrophorus Use a metal plate on a handle to transfer charge from a large charged surface.
5A10.20 electrophorus Obtain charge by induction from an electrophorus.
5A10.20 electrophorus, etc An electrophorus. is pictured along with a conducting sphere, an ellipsoidal conductor, a hollow cylinder, and a dissectible condenser.
5A10.20 electrophorus Repeat charging a metal plate many times. Animation sequence shows movement of charges.
5A10.21 electrophorus, etc. Describes using Lucite or polystyrene as the sole and a cylindrical electrophorus. with a built in neon lamp. Diagram. ALSO - newer rod and fur material, a shielding demo.
5A10.21 electrophorus Directions for making an electrophorus. from sealing wax. Use a neon discharge tube to show a flash by holding one end on the electrophorus. and then touching the other end.
5A10.22 electrophorus, etc Four demos: one illustrating the action of an electrophorus., another showing the reaction of a charged balloon to a paddle charged positive, negative, or neutral, and more.
5A10.23 cylindrical electrophorous A copper tube on a handle fits over a 1" polystyrene cylinder mounted vertically. Some discussion about how electricity is transferred on rubbing that contradicts standard approaches.
5A10.24 electrophorus - neon wand A neon wand flashes as polystyrene/metal electrophorus. is opened and closed.
5A10.30 electret
5A10.30 electret Directions for making an electret. Used the same as an electrophorus. except it is permanently charged. References.
5A10.35 equal and opposite charges
5A10.35 equal and opposite charge Two electroscopes are charged equal and opposite, then the charge is transferred from one to the other. If tape is pulled off an electroscope plate, charge will result and the tape will also charge a second electroscope with the opposite charge. Picture.
5A10.36 equality of charges Rub a rubber rod against a similar rod covered with wool in a Faraday ice pail. The electroscope shows no charge unless either of the rods is removed. Or, rub them together outside the pail and insert them separately and together.
5A10.37 electrostatic rod and cloth
5A10.37 electrostatic rod and cloth Rub a rod with a cloth, place on a pivot, show attraction between rod and cloth.
5A10.40 mercury-glass charging wand
5A10.40 shake mercury in a bottle Put some mercury in a plastic bottle with a conducting rod sticking through a stopper. shake the mercury and invert to charge the rod for a positive charge, invert a second time for negative.
5A10.40 mercury-glass charging wand A glass tube containing some mercury is covered with tin foil on one end. Either positive or negative charge may be produced.
5A10.43 mercury tube Directions for making a mercury tube that emits light when shaken. Optionally neon is introduced to produce more light.
5A10.50 cyrogenic pyroelectricity
5A10.50 cyrogenic pyroelectricity The polarization of some pyroelectric crystals increases dramatically at low temperatures.
5A10.55 heating and cooling tourmaline
5A10.55 heating and cooling tourmaline Heat a long thin crystal of tourmaline over a flame and when it cools opposite charges develop on the ends large enough to deflect an electroscope.
5A10.55 cooling and heating tourmaline A long thin crystal of tourmaline that has been immersed in liquid air will form opposite charges on the ends upon warming.
5A10.56 charge by freezing sulfur Allow molten sulfur to solidify on a glass rod, check with an electroscope.
5A10.76 stretched rubber band A stretched rubber band becomes charged positively. Any amount of charge can be removed by sliding along the band.
5A10.90 electrostatics in a hot box Perform electrostatics demonstrations in a heated box to decrease the relative humidity.

20. Coulomb's Law

5A20.10 rods and pivot With one charged rod on a pivot, use another of the same or opposite charge to show attraction or repulsion.
5A20.10 rods and pivot With one charged rod on a pivot, use another of the same or opposite charge to show attraction or repulsion.
5A20.10 rods and pivot Show attraction or repulsion with rods on a pivot or hung by a thread.
5A20.20 pith balls Suspend two small pith balls and show either attraction or repulsion.
5A20.20 Coulomb's law with pith balls
5A20.20 Coulomb's law with pith balls Charge two pith balls with an electrostatic generator, project on the wall and measure, discharge one ball, and remeasure the separation. Accuracy is typically 2%.
5A20.20 pith balls Suspend two small pith balls from a common support.
5A20.20 pith balls Charge pith balls.
5A20.21 Coulomb's law on the overhead Demonstrate Coulomb's law on the overhead with two ping-pong balls.
5A20.21 pith balls on overhead Suspend two pith balls coated with Aquadag in a clear framework on the overhead projector.
5A20.22 hollow aluminum foil balls Hollow aluminum foil balls are charged with a Van de Graaff generator.
5A20.22 hollow aluminum balls Wrap aluminum foil around a marble or ping-pong ball and then remove the ball to make a replacement for a light pith ball.
5A20.22 pith balls & variations Metal painted ping pong balls, gas filled balloons, pith balls are used as charge indicators.
5A20.23 repelling balls A small charged pith ball is repelled from a large charged sphere.
5A20.23 electric potential Bring a charged pith ball close to a like charged conductor and note the repulsive force.
5A20.25 ping pong ball electroscope
5A20.25 ping pong balls Paint a ping pong ball with silver printer circuit paint.
5A20.25 ping pong pith balls Two silver coated ping pong balls are suspended from separate supports.
5A20.25 ping-pong ball electroscope Repulsion of two charged ping-pong balls hung from nylon cord.
5A20.25 ping-pong ball electroscope Hang an electroscope made from aluminized ping-pong balls from aluminum welding rod. Picture.
5A20.25 electrostatic ping-pong deflection Attraction and repulsion between charged conductive ping pong balls.
5A20.26 ping pong ball electroscope Details of an electroscope made with ping pong balls on the ends of hanging rods.
5A20.27 image charge A large metalized styrofoam ball is mounted on a rod with a counterwieght and air bearing at the midpoint. Bring a second ball and then a highly charged metal plate near.
5A20.27 counterweighted balls Polystyrene spheres (3" dia.) are mounted on counterweighted Lucite rods.
5A20.27 counterweighted balls Pith balls are replaced by balls pivoting on counterweighted rods.
5A20.28 beer can pith balls
5A20.28 beer can pith balls Aluminum beer cans are used instead of pith balls to show repulsion of like charges.
5A20.30 mylar balloon electroscope
5A20.30 balloon electroscope Balloon electroscopes, helium filled or normal, can be painted with aluminum and charged with a Van de Graaff.
5A20.30 balloons on Van de Graaff Tape mylar balloons on conducting strings to a Van de Graaff generator.
5A20.30 Van de Graaff repulsion Hang an aluminized balloon is hung from a rod attached to the Van de Graaff electrode to demonstrate repulsion of like charges.
5A20.32 electrostatic spheres on air table
5A20.35 Coulomb's law balance The PSSC soda straw balance is adapted to make a simple Coulomb's law balance.
5A20.40 aluminum sheet electroscope Two squares of aluminum foil are suspended from wires across a glass rod.
5A20.41 large leaf electroscope A 15" length of 1 1/2" mylar tape is suspended along a brass strip.
5A20.50 measuring Coulomb's law An optical lever and damper make this apparatus useful to demonstrate Coulomb's law. Diagram, Construction details in appendix, p. 1311.

22. Electrostatic Meters

5A22.10 Braun electroscope
5A22.10 Braun electrostatic voltmeter A well balanced needle measures voltages to a few KV.
5A22.10 large Braun electroscope Build this Braun electroscope with a 2' vane. Picture, Diagram.
5A22.10 the Leybold Braun electroscope Show the Leybold Braun electroscope with some other electrostatics apparatus.
5A22.12 electroscopes and electrometers The Braun electrostatic voltmeter and Zeleny oscillating-leaf electroscope are described and pictured.
5A22.22 electroscopes Four types of electroscopes are pictured.
5A22.25 soft drink can electroscope
5A22.25 simpler soft-drink-can electroscope The tab of the soft drink can supports the electroscope leaves in this simple version.
5A22.26 leaf electrometer Modify a leaf electroscope so it discriminates polarity of charge.
5A22.30 gold leaf electroscope
5A22.30 gold leaf electroscope A gold leaf electroscope is projected with a point source.
5A22.30 projection electroscopes Lantern and shadow projecting a gold leaf electroscope, make your own electroscope.
5A22.41 vibrating reed electrometer Circuit diagram for a vibrating reed electrometer. Ten demonstrations using the device are listed.
5A22.45 oscillating electroscope An insulated indicating wire is charged by corona and rises until it touches a ground, then the cycle repeats.
5A22.50 Kelvin electrostatic voltmeter
5A22.50 Kelvin electrostatic voltmeter A rotating vane electrostatic voltmeter.
5A22.51 electrostatic voltmeter Measure voltage with a rotor and vane electrostatic voltmeter. Picture, Construction details in appendix, p.1320.
5A22.60 condensing electroscope Charges too small to be detected by an electroscope can be detected with the addition of a variable capacitor. Directions and a drawing.
5A22.65 electrometer with concentric cap. Concentric capacitors are mounted on an electrometer with the outer grounded. Insert samples in the inner to measure charge.
5A22.70 electrometer
5A22.70 Pasco equipment A Pasco electrometer along with the whole kit of Pasco accessories.
5A22.71 Pasco projection meter A remote projection meter for the Pasco electrometer.
5A22.80 electric field mill
5A22.80 electric field mill Contains short explanation of an instrument used to measure the electric field.
5A22.81 simple field mill A circuit used in a simple field mill.
5A22.90 electroscope on a diode tube An aluminum foil electroscope attached to the plate of a rectifier diode tube is discharged when the power is turned on.
5A22.91 triode electroscope relay An antenna is hooked to a grid of a triode tube that controls a relay turning on a light bulb. Charged rods brought close to the antenna turn the light on or off.
5A22.95 negative charge detector The neon light goes out in a triode circuit when negative charge is brought close to a wire connected to the grid.

30. Conductors and Insulators

5A30.10 wire versus string
5A30.10 wire versus string Connect two electroscopes together with wire or string and charge one electroscope.
5A30.10 wire versus string Connect a wire or silk thread to an electroscope and show the difference in conductivity. ALSO - some on capacitance.
5A30.15 acrylic and aluminum bars
5A30.15 conductors and insulators Aluminum and acrylic rods are mounted on a Braun electroscope. Bring a charged rod close to each rod.

40. Induced Charge

5A40.10 charging by induction Charging by induction using two balls on stands with an electroscope for a charge indicator.
5A40.10 charging by induction Charging by induction using two balls on stands.
5A40.10 electrostatic induction Use two metal spheres, a charged rod, and an electroscope. Animation shows charges.
5A40.12 induced charge Use electroscopes and proof planes to show charging by induction.
5A40.13 methods of electrostatic induction Various forms of conductors are separated in an electric field.
5A40.15 electroscope charging by induction
5A40.15 electroscope charging by induction Use conductors on the top of two electroscopes that can be brought into contact to demonstrate charging by induction.
5A40.15 induction charging Large metal bars on two electroscopes are apart when charging by induction.
5A40.16 charging electroscope by induction Touch the plate of an electroscope while holding a charged rod nearby. Next month may contain answers to impertinent questions raised by high school students.
5A40.16 charging electroscope by induction Answer to the question of an earlier Physics Teacher. Diagrams show how an electroscope is charged when touched while a charged rod is brought near.
5A40.16 charging electroscope by induction Charge an electroscope by touching while holding a charged rod near.
5A40.17 electrostatic charging by induction Pith balls touching both ends of a conductor are charged when a charged rod is brought toward one end. Use another test charge to show the polarity at each end.
5A40.20 can attracted to charged rod A hoop of light aluminum is attracted to a charged rod.
5A40.20 charge propelled cylinder
5A40.20 can attracted to charged rod A hoop of light aluminum is attracted to a charged rod.
5A40.23 charged ball attracted to ground A metalized ball is attracted to a grounded aluminum sheet when a charge is applied to the ball.
5A40.23 suspended electrophorus disc Raise an electrophorus. disc off the plate with a helical spring, touch the disc to remove induced charge, and show the spring lengthens.
5A40.24 blow soap bubbles at Van de Graaff Blow neutral soap bubbles at a Van de Graaff generator for intriguing induction effects. Try double bubbles.
5A40.25 paper sticks on board
5A40.25 paper sticks on the board Hold a piece of paper on a slate blackboard and rub it with fur.
5A40.25 rub paper Rub paper with cat fur while holding it on the board.
5A40.26 familiarity breeds contempt Cork filings are first attracted to a charged rod by induced charge, then repelled as they become charged by conduction.
5A40.30 2" x 4"
5A40.30 2" x 4" Induced charge is used to move a 2x4 balanced on a watch glass.
5A40.30 conductivity of a "two by four" Rotate a 2x4 by bringing a charged rod close.
5A40.30 wooden needle The "needle" is a six foot 2X4.
5A40.35 metal rod attraction
5A40.35 metal rod attraction Place a metal rod on a pivot and show attraction to both positive and negative charged rods.
5A40.36 forces between electrodes A ball on a flexible rod is attracted to an electrostatic generator by the induced charge.
5A40.40 deflection of a stream of water
5A40.40 deflection of a stream of water A charged rod deflects a stream of water.
5A40.40 deflection of a water stream A charged rod is held near a stream water flowing from a nozzle.
5A40.42 deflection of water stream At different ranges the water stream 1) the jet is smooth from nozzle to sink, 2) is attracted to the rod, 3) breaks up into small drops.
5A40.43 Raleigh fountain A charged rod held near a stream of water directed upward breaks it into drops.
5A40.60 electrostatic generator principles
5A40.60 electrostatic generator principles Same as AJP 37(10),1067.
5A40.60 electrostatic generator principles Manipulate two metal cans and move a metal ball back and forth to show how charging by induction and charge transfers build up charge.
5A40.60 electrostatic generator principles Two cans and two balls and cross your hands.
5A40.70 Kelvin water dropper
5A40.70 Kelvin water dropper Sparks are produced by falling water.
5A40.70 Kelvin water dropper Sparks are produced by water falling through two rings connected by an "x" arrangement to opposite receivers.
5A40.70 Kelvin water dropper A simple Kelvin water dropper made with shower heads enclosed in cans. Diagram.
5A40.70 Kelvin water dropper Explanation of and directions for building a Kelvin water dropper. Picture, construction details in appendix, p.1311.
5A40.70 Kelvin water dropper A diagram and some construction details are given for the Kelvin water dropper. A "dry water dropper" using steel balls is mentioned.
5A40.70 Kelvin water dropper A Kelvin water dropper discharges a small neon lamp. Animation sequence shows principles of operation.
5A40.72 Kelvin water dropper - ac The Kelvin water dropper is extended to multiphase, multifrequency operation by considering N streams and N cans. A five can version is shown.
5A40.73 almost Kelvin water dropper Water drops through a paraffin coated funnel into a brass cup. The funnel and cup are connected to a electroscope.

50. Electrostatic Machines

5A50.05 electrostatic generators General discussion of electrostatic machines.
5A50.10 Wimshurst machine Crank a Wimshurst generator.
5A50.10 Wimshurst machine An explanation of how the Wimshurst charges by induction.
5A50.10 induction generator Shows Wimshurst machine. Animation sequence shows principles of operation.
5A50.11 Wimshurst machine Picture of a small Wimshurst machine.
5A50.12 ac Wimshurst The Wimshurst design is extended to produce three phase ac at 18 kV and 2 Hz.
5A50.15 Toepler-Holtz machine
5A50.15 Toepler-Holtz machine A large antique Holtz machine used to generate high voltages for old X-ray machines. Will produce a 10" spark.
5A50.16 two-inductor electrostatic generator A Wimshurst type generator simplified with only one disk for pedagogical purposes. The references for this article are found in AJP 51(9),861.
5A50.17 fur and record generator A series of pictures illustrate construction of a simple electrostatic generator built using a hand drill, LP record, and fur.
5A50.20 dirod electrostatic machine
5A50.20 dirod electrostatic machine A rotating electrostatic machine made with a disk and rods. Picture, Diagrams, Construction details in appendix, p. 1312.
5A50.30 Van de Graaff generator Show sparks from a Van de Graaff generator to a nearby grounded ball.
5A50.30 Van de Graaff Design of a good size Van de Graaff.
5A50.30 electrostatic generating machines Directions for building a Van de Graaff generator. Reference.
5A50.31 Van de Graaff principles
5A50.31 Van de Graaff theory A note on the theory of the Van de Graaff.
5A50.31 electrostatic generator A very practical article covering theory, maintenance, and belt fabrication.
5A50.31 electrostatic generator An explanation of the Van de Graaff generator.
5A50.31 Van de Graaff generator Shows a Van de Graaff with paper streamers, then a long animated sequence on the principles of operation.
5A50.32 Van de Graaff vs. Simon Theories of Van de Graaff and Simon (AJP 22,318 (1954)) are compared and experiments yield results in accordance with the Simon theory.
5A50.34 improvements to toy Van de Graaff Double the length of the spark with two modifications.
5A50.34 improvements on the toy Van de Graaf Two improvements to the toy Van de Graaff generator.
5A50.50 Franklin's electrostatic machines
5A50.50 Franklin's electrostatic motors Models of Franklin's first two electric motors are shown.
5A50.51 electrostatic motor A polyethylene bottle spins as a Wimshurst is connected to brushes alongside the bottle.
5A50.52 electrostatic motor A motor operated by electrostatic charges drawn from an electrostatic generator. Picture.
5A50.52 electrostatic motor Use a large static machine to drive a smaller one as a motor.
5A50.53 elecrostatic motor An electrostatic motor with a vane type rotor.
5A50.55 atmospheric electric field motor Report on the construction of an electret type and corona type motor for operation from the earth's electric field.


10. Electric Field

5B10.10 hair on end While standing on an insulated stool, charge yourself up with a Van de Graaff generator.
5B10.10 hair on end While standing on an insulated stool, charge yourself up with a Van de Graaff generator.
5B10.10 hair on end Stand on an insulated stool and hold on to a terminal of a static machine. Disconnect the condensers.
5B10.13 pithball plate and flying balls Place a plate with pith ball hanging on strings on an electrostatic generator. Also place a cup filled with styrofoam balls on an electrostatic generator.
5B10.15 Van de Graaff streamers
5B10.15 Van de Graaff streamers Attach ribbon streamers to the top of a Van de Graaff generator.
5B10.15 Van de Graaff streamers A small stand with thin paper strips is placed on an electrostatic generator.
5B10.15 Van de Graaff with streamers Show Van de Graaff with paper streamers, then hair on end.
5B10.16 recoiling tentacles Place the electrostatic plume made out of nylon rope near the other terminal of the Wimshurst machine.
5B10.21 electric rosin Melt rosin in a metal ladle and attach to a static machine. When the machine is cranked and the rosin slowly poured out, jets of rosin follow the electric field.
5B10.22 electrostatic painting Clip the can to ground and a metal object to be painted to the Van de Graaff generator. Point out that the paint goes around to the back too, and it is thickest on the edges.
5B10.23 MgO smoke Fill an unevacuated bell jar with MgO smoke and they will form three dimensional chain-like agglomerates between electrodes.
5B10.23 orbiting foil Throw a triangle of aluminum foil into the field of a Van der Graaff and it comes to equilibrium mid-air. Give it a half-twist, and it will orbit in a horizontal circle below the sphere.
5B10.24 charge motion in an electric field A charged ball on a dry ice puck is launched toward a Van de Graaff generator. The motion is recorded with strobe photography.
5B10.25 confetti (puffed wheat) Confetti (puffed wheat, styrofoam peanuts) flies off the ball of an electrostatic generator.
5B10.25 styrofoam peanuts
5B10.25 confetti on electrostatic generator Confetti flies off the ball of an electrostatic generator.
5B10.25 streamers Fray the end of a nylon clothesline and charge with an electrostatic machine to show repulsion.
5B10.26 electrified strings
5B10.26 eletrified strings A bunch of hanging nylon strings are charged by stroking with cellophane causing repulsion.
5B10.26 electrified strings Charge a mop of insulating strings.
5B10.26 shooting down charge Use the piezoelectric pistol to discharge the electrified strings.
5B10.30 electric chimes
5B10.30 electric chimes A ball bounces between charged metal chimes.
5B10.30 electric chimes Insert a metalized ping-pong ball between two highly charged metal plates.
5B10.30 electric chimes A small metal ball hangs on a thread between two bells attached to an electrostatic machine.
5B10.30 electrostatic ping-pong balls Conductive ping pong balls bounce between horizontal plates charged with a Wimshurst.
5B10.31 jumping particles Aluminum powder bounces between two horizontal plates 1 cm apart attached to a static machine. Metalized pith balls bounce between an electrode at the top of a bell jar and the plate.
5B10.32 Van de Graaff chime Toss a small foil near the charged sphere (see AJP 32(1),xiv - 5B10.33) and then bring a grounded ball close to show the chime effect.
5B10.33 electrostatic ping-pong A fluffy cotton ball travels back and forth between an electrostatic generator and a lighted cigar.
5B10.35 electrostatic ping pong
5B10.35 electrostatic ping pong Bounce a conducting ball hanging between two plates charged with a Wimshurst.
5B10.40 fuzzy fur field tank
5B10.40 fuzzy fur field tank "Fur" in mineral oil aligns along field lines from charged electrodes.
5B10.40 "velveteens" Fine black fiber clippings in castor oil are used to show electric field between electrodes.
5B10.40 electric fields between electrodes Charged electrodes are placed in a tank of mineral oil containing velveteen and the pattern is projected on the overhead.
5B10.40 fuzzy fur field tank Bits of material suspended in oil align with an applied electric field. Several pole arrangements are shown.
5B10.40 electric field A pan on the overhead projector contains particles in a liquid that align with the electric field.
5B10.41 repelled air bubbles A stream of air bubbles in an oil bath are repelled in the region of an inhomogeneous field.
5B10.42 epsom salt on plate Sprinkle Epson salt on a glass plate with two aluminum electrodes. Tap to align the crystals.
5B10.43 ice filament growth An ice filament pattern shows the electrical field configuration. Place a PZT transducer on a block of dry ice.
5B10.50 mapping force with "electric doublet Two pith balls charged oppositely and hanging from a rod are used to map out the field in the region of charged conductors.
5B10.51 plotting equipotential lines A method for plotting equipotential lines from electrodes in a pan on water.
5B10.52 finger on the electrophorus Charge and electrophorus., then trace a circle on it with your finger and probe the resulting field with a pith ball on a long thread.
5B10.53 extent of electric field Hold an electroscope several feet away from a static machine and observe the electroscope leaves rise and fall as sparking occurs.
5B10.54 mapping field potential, voltage A wire held in the flame of a candle and attached to a grounded electroscope is held near a Van de Graaff generator. Mount two candles on a insulator and attach the second to the case of the electroscope to measure voltage.
5B10.54 mapping potential field A small alcohol lamp attached to an electrostatic voltmeter can be used to map potential fields.
5B10.55 liquid crystal mapping An electrode configuration is painted onto a conducting paper with temperature sensitive encapsulated liquid crystals. Joule heating causes color changes.
5B10.55 liquid crystal mapping An alternate method (to AJP 41(12),1314) of preparing liquid crystal displays of electric fields.
5B10.57 double brass plate measurement The field around a large sphere is measured by separating two brass plates and measuring the charges with a ballistic galvanometer.
5B10.58 electric field indicator A point on the end of a 500 Mohm resistor connects to a neon bulb in parallel with a small capacitor.
5B10.60 electric fields of currents Current carrying conductors are made of transparent conducting ink on glass plates. Sprinkle on grass seeds to demonstrate the electric lines of force inside and outside the conducting elements.
5B10.61 electric fields of currents Draw a circuit on glass or mylar with a soft lead scoring pencil. Dust the glass with small fibers while the current is flowing.
5B10.62 water drop model of charged particle A water drop model demonstrates the motion of a stream of charged particles in an electric field.
5B10.70 other surfaces see 8C20.20,1L20.10
5B10.70 rubber sheet field model
5B10.70 rubber sheet model for fields Roll balls over a 6'x4' frame with a stretched rubber surface, distorting it with dowels to represent charges.
5B10.70 model of field potential A sheet of rubber is pushed up and down with dowels to represent positive and negative charges.
5B10.71 stretched membrane field model A rubber sheet stretched over a large quilting hoop models electric fields.

20. Gauss' Law

5B20.10 Faraday's ice pail With a proof plane and electroscope, show charge is on the outside of a hollow conductor.
5B20.10 Faraday's ice pail - induction A charged ball is moved in and out of the Faraday ice pail and the electroscope deflection noted, then touched to the inside of the pail.
5B20.10 Faraday's ice pail With a proof plane and electroscope, show charge is on the outside of a hollow conductor. ALSO, "Faraday's bag".
5B20.10 Faraday ice pail Charge a bucket with a Wimshurst and transfer charge from the inside and outside of the bucket to an electroscope.
5B20.11 big Faraday ice pail A 55 gal. drum Faraday ice pail and other stuff.
5B20.12 Faraday ice pail A Faraday ice pail made of two concentric wire mesh cylinders connected to a Braun electroscope.
5B20.15 Faraday's ice pail on electroscope
5B20.15 Faraday's ice pail on electroscope A charged metal pail sits on an electroscope. A proof plane transfers charge from the inside or outside to another electroscope.
5B20.15 butterfly net experiment Turn a charged butterfly net inside out and the charge is still on the outside.
5B20.16 Faraday ice pail on electroscope A charged copper beaker placed on an electroscope is touched on the outside or inside with a proof plane.
5B20.30 electroscope in a cage
5B20.30 sheilded electroscope A charged rod is brought close to a gold leaf electroscope in a wire mesh cage.
5B20.30 electroscope in a cage Enclose an electroscope in a cage of heavy wire screening.
5B20.30 Faraday cage Bring a charged rod near a Braun electroscope, then cover the electroscope with a wire mesh cage and repeat.
5B20.31 electroscope in a cage/Wimshurst
5B20.31 electroscope in a cage on Wimshurst A screen cage shields an electroscope from a charged rod.
5B20.33 pith balls in a cage Metal coated pith balls are suspended inside and outside of a metal screen cylinder attached to a electrostatic machine.
5B20.35 radio in a cage Place a wire mesh cage over a radio.
5B20.35 radio in a cage
5B20.35 radio in Faraday cage Place a wire mesh cage over a radio.
5B20.36 VTVM in a cage Mount the inputs to a VTVM in a Faraday cage. Show charge transfer from plastic strips.

30. Electrostatic Potential

5B30.10 surface charge density - balls
5B30.10 surface charge density - balls Separate several pairs of balls of different diameters attached to a Wimshurst by the same distance.
5B30.10 surface charge density Sets of balls of different radius but the same separation are simultaneously attached to a Wimshurst.
5B30.20 charged ovoid
5B30.20 charged ovoid Proof planes of the same area take charge off the round or pointed end of a zeppelin shape.
5B30.20 surface charge density Proof planes of the same area take charge from the flat or pointed end of a charged zeppelin shaped conductor.
5B30.20 charged Zeppelin Use a proof plane and electroscope to compare charge densities at different points on a egg shaped conductor.
5B30.22 charge distribution on spheres Read this one. Determine the charge distribution as spheres are brought close to a charged sphere.
5B30.24 surface charge density with cans Transfer charge from the edge of a can on a source to the inside of a second can.
5B30.25 charge on spheres Spheres of different diameters are brought to the same potential and inserted into a Faraday ice pail to show different charges.
5B30.26 spark gaps Connect an electrostatic voltmeter to the terminals of an static machine and observe the voltage while varying the spark gap.
5B30.27 measure the second derivative of pot A two point probe measures potential, and a five point probe measures the second derivative of potential. Diagram.
5B30.28 potential during discharge An electroscope is connected to the ball of the electric chime to observe the decrease on potential as the ringing diminishes.
5B30.30 lightning rod Insert a sphere and point of the same height between horizontal metal plates charged by a Wimshurst.
5B30.30 lightning rod Insert a sphere and point of the same height between horizontal metal plates charged by a Wimshurst.
5B30.30 lightning rod Sparks jumping from a plane to a sphere will stop when a point is inserted.
5B30.30 lightning rod Sparks discharge from a large ball suspended over a model house with a small ball in the chimney until a point is raised above the small ball.
5B30.35 point and ball with Van de Graaff
5B30.35 point and ball with Van de Graaf Hold a ball close to a Van de Graaff generator and then bring a point close.
5B30.35 Van de Graaff and wand With paper streamers as a field indicator, bring a ball and point close to the Van de Graaff.
5B30.40 electric wind
5B30.40 electric wind A point attached to a Wimshurst blows a candle flame.
5B30.40 electric wind A candle between pointed and plane electrodes attached to a Wimshurst will blow the flame.
5B30.40 electric wind A candle flame held near a point connected to the positive side of an electrostatic generator will repel the flame as if there is a breeze of ions.
5B30.40 point and candle Attach a sharp point to one terminal of a Toepler-Holtz generator and point it at a candle flame.
5B30.41 history of the electric wind Covers discovery and early investigations, the dust controversy, and recent studies and applications.
5B30.42 corona discharge in air The corona discharge from a point towards a candle flame and a pinwheel spinning.
5B30.43 cooling with electric wind The electric wind from needle points cools a glowing nichrome wire heater.
5B30.44 corona current A 1/2 Meg resistor in series with a galvanometer measure the current in a corona discharge from an electrostatic machine.
5B30.45 corona discharge A charged aluminum rod with a needle at one end will charge a nearby sphere with like charge if the needle is pointed to the sphere and with opposite charge if the needle is pointed away.
5B30.45 escape of charge from a point When charge is induced on an electrode with a point, the induced charge will escape and the charge on the induced electrode will be the same as on the inducing electrode.
5B30.45 charge by pointing Charge a conductor by proximity to a point attached to a static machine.
5B30.46 discharging from a point Three balloons filled with illuminating gas are suspended from a point and charged. The blunt end of a brass rod has little effect but the pointed end discharges the balloons when pointed at them.
5B30.46 darning needle discharge The blunt end of a darning needle is placed on the charged conductor of an electroscope and the electroscope is discharged.
5B30.47 collapse the field The point of a grounded needle is brought near a charged tinsel tassel and the tassel collapses.
5B30.48 electrical discharge from water drop A drop of water placed on the positive electrode of a Wimshurst will form a corona but spit droplets when placed on the negative electrode.
5B30.49 point cathode effect A point 1s biased to 1200 V in a Wilson cloud chamber.
5B30.50 pinwheel
5B30.50 pinwheel A pinwheel spins when attached to a Wimshurst generator.
5B30.50 electrostatic pinwheel A conducting pinwheel spins when connected to a Wimshurst.
5B30.50 pinwheel A pinwheel rotates when connected to either terminal of a static machine.
5B30.50 pin wheel Place a pinwheel on a Van de Graaff generator.
5B30.51 electrostatic solar system A double pinwheel rotates when connected to a Wimshurst.
5B30.60 Cottrell precipitator
5B30.60 Cottrell precipitator
5B30.60 electrostatic precipitator Clear smoke in a chimney with points are connected to a Wimshurst.
5B30.60 Cottrell precipitator Clear a smoke filled tube by a discharge from wire points.
5B30.60 smoke precipitation Demonstrate smoke particles precipitating in a strong electric field in an artificial chimney.
5B30.60 smoke precipitation Attach a Wimshurst to terminals at each end of a glass tube filled with smoke.
5B30.90 energy in the discharge Light some alcohol or a Bunsen burner with the spark from a static machine.
5B30.91 gas explosion by spark A spark plug hooked to a static machine is used to explode a mixture of hydrogen and oxygen in a closed container.
5B30.95 human chain All students hold hands with one student holding one knob of a static machine and the other holding a metal rod near the other knob.
5B30.96 discharge through body A student standing on the floor touches other students standing on insulated stands holding on to the two knobs of a static machine.


10. Capacitors

5C10.10 sample capacitors
5C10.10 sample capacitors Show many capacitor examples.
5C10.10 capacitors Several types of capacitors are shown.
5C10.15 simple spherical capacitor Charge a 8" sphere several times with an electrophorus, then repeat with a insulated conductor near, then repeat with a grounded conductor near. The number of sparks required to reach a potential varies.
5C10.20 parallel plate capacitor Change the spacing of a charged parallel plate capacitor while it is attached to an electroscope.
5C10.20 parallel plate capacitor Change the spacing of a charged parallel plate capacitor while attached to an electroscope.
5C10.20 field and voltage Vary the spacing of a charged parallel plate capacitor while the voltage is measured with an electroscope.
5C10.20 parallel plate capacitor Charge a simple capacitor of two parallel movable plates and the divergence of electroscope leaves varies as the plates are moved.
5C10.20 capacitance and voltage Separate charged plates while an electroscope is attached.
5C10.20 parallel plate capacitor Charge parallel plates with a rod, watch the electroscope as the distance between the plates is changed. Animation sequence.
5C10.21 battery and separable capacitor
5C10.21 battery and separable capacitor Charge a parallel plate capacitor to 300 V, then move the plates apart until an electroscope deflects.
5C10.30 dependence of capacitance on area
5C10.30 dependence of capacitance on area As a chain is lifted out of a hollow charged conductor on an electroscope, the deflection decreases. When let back down, it increases again.
5C10.31 dependence of area on capacitance A long rectangular sheet of charged tin foil is rolled up while attached to an electroscope.
5C10.32 dependence of capacitance on area Hook up a charged radio tuning condenser to an electroscope.
5C10.33 Chinese lantern capacitor Vary the length of an aluminum painted Chinese lantern to show the change of capacitance.
5C10.35 rotary capacitor
5C10.35 rotary capacitor Charge a large rotary capacitor with a rod and watch an electroscope as the overlap is changed.
5C10.40 C=i/(dv/dt) demonstrator Vary a potentiometer so that a constant current is maintained while charging a capacitor from a 90 volt battery. Measure the time.
5C10.50 inducing current with a capacitor A charged ball moving between the plates of a parallel plate capacitor will induce a current in the external circuit.

20. Dielectric

5C20.10 capacitor with dielectrics Insert and remove a dielectric from a charged parallel plate capacitor while it is attached to an electroscope.
5C20.10 capacitor with dielectrics Insert and remove a dielectric from a charged parallel plate capacitor while attached to an electroscope.
5C20.10 dielectrics The voltage is measured with an electroscope as dielectrics are inserted between parallel plates of a charged capacitor.
5C20.10 capacitor with dielectrics Various dielectrics are inserted between two charged metal plates to show the difference in deflection on an electroscope.
5C20.10 parallel plate capacitor dielectrics Charge a parallel plate capacitor with a rod, insert dielectrics and observe the electroscope. Animation.
5C20.11 capacitor with dielectrics Six demonstrations with a parallel plate capacitor and dielectrics.
5C20.12 equation Q=CV The bottom of a parallel plate capacitor is mounted on an electroscope, charge the top plate, touch the bottom, lift off the top.
5C20.13 C-V relationships An automated device to charge a capacitor and separate the plates. Reference: AJP 22(3),146.
5C20.14 intervening medium Bring a charged rod close to an electroscope and interpose various materials between the two.
5C20.17 helium dielectric
5C20.17 helium dielectric Helium is blown into a charged parallel plate capacitor.
5C20.20 force on a dielectric
5C20.20 force on a dielectric A counterbalanced acrylic dielectric is pulled down between parallel plates when they are charged with a small Wimshurst generator.
5C20.21 force on a dielectric - glass plate A microscope slide is pulled into the gap between parallel plates of a capacitor.
5C20.22 force on a dielectric A elongated paraffin ellipsoid in a parallel plate capacitor turns when the field is turned on, kerosene climbs between parallel plates.
5C20.25 attraction of charged plates
5C20.25 attraction of charged plates A brass plate fitted with an insulating handle can lift a lithographic stone plate when 300 V dc is applied.
5C20.26 attraction of charged plates The top plate of a parallel plate capacitor is mounted on a triple beam balance so the force can be measured with and without dielectrics as the voltage is varied. Pictures, Construction details in appendix, p.1322.
5C20.27 attraction of charged plates The permittivity of free space is measured using a Mettler balance to determine the force between the plates of a parallel plate capacitor.
5C20.30 dissectible condenser A capacitor is charged, disassembled, passed around, assembled, and discharged with a spark.
5C20.30 dissectible condenser Same as Ed-3.
5C20.30 dissectible condenser A capacitor is charged, disassembled, passed around, assembled, and discharged with a spark.
5C20.30 dissectible condenser The inner and outer conductors of a charged Leyden jar are removed and brought into contact, then reassembled and discharged in the usual manner.
5C20.30 dissectible capacitor Charge a capacitor and show the discharge, then charge again and take it apart. Handle it, try to discharge it, reassemble it, and discharge it.
5C20.35 bound charge
5C20.35 bound charge
5C20.35 bound charge The two coatings of a Leyden jar can be grounded successively without much loss of charge. When the two coatings are connected, there is a discharge.
5C20.40 impedance of a dielectric Place a small parallel plate capacitor in series with a phonograph pickup. Insert different dielectrics. High dielectrics have low impedance.
5C20.50 breath figures Blow on a glass plate that has been polarized with the image of a coin.
5C20.51 Lichtenberg figures A pattern is traced on a dielectric from the two polarities of a charged Leyden jar. Litharge and flowers of sulfur sprinkled on adhere to the areas traced out with the different polarities.
5C20.60 displacement current
5C20.60 displacement current A toroidal coil is either placed around a wire leading to a large pair of capacitor plates to demonstrate Ampere's law or inserted between the capacitor plates to demonstrate displacement current.
5C20.61 displacement current Measure the displacement current in a barium titanate capacitor.
5C20.61 displacement current comment comment More semantics.
5C20.61 displacement current comment The experiment in AJP 32,916,(1964) has nothing to do with displacement current in Maxwell's sense.
5C20.61 displacement current Measure the displacement current in a barium titanate capacitor. Diagrams, Derivation.

30. Energy Stored in a Capacitor

5C30.10 Leyden jar and Wimshurst
5C30.10 Leyden jar Sparks from a Wimshurst are no longer but are much more intense when a Leyden jar is connected.
5C30.10 Leyden jars on Toepler-Holtz The Topler-Holtz produces weak sparks without the Leyden jars and strong less frequent sparks with the jars connected.
5C30.15 exploding capacitor
5C30.15 grounded Leyden jar Charge a capacitor with a Wimshurst, ground each side separately, spark to show the charge is still there.
5C30.20 short a capacitor Charge a large electrolytic (5000 mfd) capacitor to 120 V and short with a screwdriver.
5C30.20 short a capacitor A 5600 microF capacitor is charged to 120 V and shorted.
5C30.20 exploding capacitor Four 1000 microF capacitors are charged to 400 V storing about 320 Joules. Short them with a metal bar.
5C30.25 capacitor and calorimeter Discharge a capacitor into a resistor in an aluminum block with an embedded thermistor to measure the temperature increase.
5C30.30 light the bulb see 5F30.10
5C30.30 light a bulb with a capacitor Charge a large electroylitic capacitor and connect it to a lamp.
5C30.30 light the bulb A 5600 microF capacitor is charged to 120 V and discharged through a light bulb.
5C30.35 lifting weight with a capacitor
5C30.35 energy stored in a capacitor A capacitor is discharged through a small motor lifting a weight.
5C30.35 lifting a weight with a capacitor A DC motor lifts a weight powered by a charged capacitor.
5C30.36 discharge a capacitor thru wattmeter A high impedance low rpm dc motor (wattmeter) is used to discharge a capacitor.
5C30.37 charge on a capacitor A capacitor is discharged through a ballistic galvanometer.
5C30.37 capacitors and ballistic galv Charge different capacitors to different voltages and discharge through a ballistic galvanometer.
5C30.40 series/parallel Leyden jars
5C30.40 addition of potentials Charge Leyden jars in parallel and discharge, charge in parallel again and connect in series before discharging. Compare length and intensity of the sparks.
5C30.41 series and parallel condensers Charge four Leyden jars in parallel and discharge singly and with three together. Next charge three in series with one in parallel and discharge singly and three in series. Compare length and intensity of sparks.
5C30.42 series/parallel capacitors
5C30.42 series/parallel capacitors Charge a single capacitor, two series capacitors, and two parallel capacitors to the same potential and discharge through a ballistic galvanometer.
5C30.50 Marx and Cockroft-Walton
5C30.50 Marx and Cockroft-Walton circuits Intentionally low voltage models of the Marx generator and the Cockroft-Walton circuit allow the waveforms to be shown as a demonstration without high voltage probes or danger.
5C30.50 Marx generator Switching capacitors from parallel to series to generate high voltages.
5C30.50 Arkad'ev capacitor-bank transformer Switching of charged capacitors from parallel to series.
5C30.60 residual charge
5C30.60 residual charge Charge and discharge a Leyden jar, Wait a few seconds and discharge it again.
5C30.61 residual charge After discharging a Leyden jar, light a neon tube up to 100 times. Also - show the polarity of charge on the dielectric with a triode.


10. Resistance Characteristics

5D10.10 resistor assortment
5D10.10 resistor assortment
5D10.11 scaled up resistor box Rebuild an old resistance box with larger numbers.
5D10.20 characteristic resistances
5D10.20 characteristic resistances Connect one meter lengths of various wires in series and measure the voltage across each.
5D10.20 characteristic resistance Measure voltages on a commercial board with seven one meter lengths of various wires is series so all carry the same current.
5D10.20 resistance wires Place 6V across a set of wires of different lengths and/or diameters and measure the currents.
5D10.22 resistance characteristic of arc Measure the current and potential across a small arc as the series resistance is varied.
5D10.40 resistance model
5D10.40 resistance model Balls are rolled down an incline with pegs.
5D10.40 model of resistance A ball is rolled down a board with randomly spaced nails.
5D10.40 charge motion demonstrator Small balls are rolled down a board with nails scattered in an almost random pattern. Diagram.
5D10.40 electron motion model Ball bearings are simultaneously rolled down two ramps, one with pegs and one without.
5D10.50 current model with Wimshurst

20. Resistivity and Temperature

5D20.10 wire coil in liquid nitrogen A lamp glows brighter when a series resistance coil is immersed in liquid nitrogen.
5D20.10 resistance at low temperature A lamp glows brighter when a series resistance coil is immersed in liquid air.
5D20.10 cooled wire A copper coil in series with a battery and lamp is immersed in liquid nitrogen.
5D20.11 resistance at low temperature A "C" battery, 3 V flashlight bulb, and a copper wire coil make a hand held temp coefficient of resistivity apparatus.
5D20.12 audible temp-dependent resistance The resistor plunged into liquid nitrogen is part of a voltage controlled oscillator that drives a speaker.
5D20.12 cooling Current is increased in a long U of iron wire until it glows, then half is inserted into a beaker of water.
5D20.14 superconducting wire Cool a coil of NbTi wire in a series circuit with a 12 volt car battery and lamp first in liquid nitrogen, then helium. The voltage across the coil is monitored and the lamp brightness is observed.
5D20.15 flame and liquid nitrogen
5D20.15 flame and liquid nitrogen Resistance coils are heated and cooled with a test light bulb in series.
5D20.15 temperature dependence of resistance Two sets of bulbs in series with coils, one put in liquid nitrogen and the other in a flame.
5D20.16 temperature coefficent of resistance Two coils of different material but the same resistance are placed in a Wheatstone bridge and either is heated or cooled.
5D20.20 iron wire in flame Heat a coil of iron wire in series with a battery and a lamp and the lamp will dim.
5D20.20 iron wire in a flame A coil of forty turns of iron wire is heated in a flame while connected in series with a light bulb circuit.
5D20.20 putting the light out by heat A coil of iron wire wound on a porcelain core in series with a lamp and battery is heated until the lamp goes out.
5D20.20 heated wire Heat a coil of iron wire in series with a battery and a lamp.
5D20.21 flame A coil of nickel wire connected to a battery and galvanometer is heated in a flame.
5D20.30 carbon and tungsten light bulbs
5D20.30 pos and neg resistance coefficients Measure current and resistance at various voltages for a carbon and tungsten bulb.
5D20.30 carbon and tungsten lamps Plot current vs. voltage for carbon and tungsten lamps.
5D20.31 resistance of light bulbs The V/I curves for tungsten and carbon filament lamps are shown on a dual trace storage oscilloscope.
5D20.32 temperature of incandescent lamps Two silicon solar cells with interference filters measure the light at different wavelengths for use in determining the temperature of the filament.
5D20.40 resistance thermometer Attach No. 14 copper leads to a platinum coil and use with a Wheatstone bridge.
5D20.50 thermistors
5D20.50 thermistors Use a good kit of commercial thermistors and display the differential negative resistance of a fast thermistor on a transistor curve tracer.
5D20.50 thermistor Show the resistance of a thermistor placed in an ice water bath.
5D20.60 conduction in glass at high temp
5D20.60 conduction in glass
5D20.60 conduction in glass at high temp A simple version of glass conduction using binder clips and window glass.
5D20.60 conduction in glass at high temp Heat a capillary tube in a Bunsen burner until it is hot enough to sustain a current that maintains a bright glow.
5D20.60 conduction in glass Heat a glass tube with a flame until it is hot enough to sustain conduction. Vary the current by changing the ballast resistance.
5D20.61 negative temp coeff of resistance A Nerst glower must be heated with a flame until the resistance is low enough to sustain electrical heating.

30. Conduction in Solutions

5D30.10 conduction through electrolytes
5D30.10 conductivity of solutions Dip two metal electrodes in series with a light bulb in various solutions.
5D30.10 conduction thru electrolytes Immerse two copper plates in series with a lamp in distilled water, add barium hydroxide, then sulfuric acid.
5D30.10 conduction thru electrolytes Put two copper plates in series with a lamp in distilled water and salt or acid is added.
5D30.10 conductivity of solutions Two electrodes in series with a 110 V lamp are dipped into distilled water, salt water, a sugar solution, a vinegar solution, and tap water.
5D30.13 salt water string
5D30.15 electrolytic conduction on chamios Suspend a chamois between ringstands, show no conduction with a battery, resistor, meter. Soak in distilled water, repeat, then sprinkle on salt
5D30.20 migration of ions
5D30.20 speed of ions Show KMnO4 migrating with current towards the positive electrode in KNO3.
5D30.20 migration of ions Permanganate ions migrate in an electric field.
5D30.21 ionic speed Dip two platinum electrodes into an ammoniated copper sulfate solution containing some phenophthalein.
5D30.22 ionic speed Blue moves from the anode of in a potassium chloride gel when 120 volts is applied.
5D30.23 ionic speed Measuring the speed of hydrogen and hydroxyl ions in a potassium chloride gel.
5D30.30 pickle glow

40. Conduction in Gases

5D40.10 Jacob's ladder A arc rises between rabbit ear electrodes attached to a high voltage transformer.
5D40.10 Jacob's ladder A arc rises between rabbit ear electrodes attached to a high voltage transformer.
5D40.10 Jacob's ladder A spark forms across "rabbit ears" on a 15 KV transformer.
5D40.10 Jacob's ladder Jacob's ladder and other spark demonstrations. Diagram.
5D40.10 climbing spark A 15 KV transformer is hooked to rabbit ears.
5D40.10 Jacob's ladder Apply high voltage AC to rabbit ears.
5D40.20 conduction of gaseous ions
5D40.20 conduction of gaseous ions A nearby flame will discharge an electroscope.
5D40.21 discharge with flame A flame connected to a high voltage source is inserted between charged parallel plates.
5D40.25 blowing ions by a charged plate Compressed air blows ions from a flame through the area between charged parallel plates onto a mesh hooked to an electrometer.
5D40.25 discharge by ions in a tube Electrodes at the bottom, middle, and top of a tube are connected to an electrometer while a Bunsen flame is burned at the bottom.
5D40.27 recombination of ions Ions from a flame are drawn past a series of charged plates attached to a Zeleny electroscope.
5D40.28 separating ions from flame Shadow project a flame between two charged metal plates to observe separation of gas into two streams of oppositely charged ions.
5D40.30 ionization by radioactivity
5D40.30 ionization by radioactivity Discharge an electroscope with a radioactive source.
5D40.32 ionization in air Various sources of ionization are brought near parallel wires attached to a 100 V battery and a Zeleny electroscope.
5D40.33 saturation The voltage across a plate close to a wire mesh is increased with a radioactive source nearby and the current is observed with a Zeleny electroscope.
5D40.34 ion mobilities A second mesh is inserted into the apparatus of A-2 and an alternating potential increased until the electroscope oscillates.
5D40.35 conduction in air by ions An electrometer measures the current between parallel plates as a flame is burned between them or an alpha source is held nearby.
5D40.36 Cerberus smoke detector Combustion products decrease conductivity in a chamber with an alpha source.
5D40.40 conduction from a hot wire
5D40.40 conduction from hot wire A constantan wire held near a charged electroscope causes discharge when it is heated red hot.
5D40.41 thermionic effect see 5P10.11
5D40.41 thermionic effect in air A Zeleny electroscope indicates electron emission from a wire when it is heated.
5D40.42 thermionic emisson
5D40.42 thermionic emission A commercial tube. Apply 90 V forward and reverse and monitor the current.
5D40.50 neon bulb
5D40.50 neon bulb resistivity A neon lamp lights at about 80 V and shuts off at about 60 V.
5D40.80 x-ray ionization
5D40.80 ionization by X-rays Discharge an electroscope with X-rays.
5D40.80 x-ray ionization Discharge an electroscope with x-rays.
5D40.81 ionization by X-rays An X-ray beam is passed through a simple ionization chamber.
5D40.99 electrohydrodynamics read this again - practical examples are ink jet printing and electrically driven convection.


20. Electrolysis

5E20.10 electrolysis of water
5E20.10 electrolysis of water DC passed through slightly acidic water evolves hydrogen and oxygen at the electrodes.
5E20.10 gas coulombmeter The volume of gas from electrolysis is measured.
5E20.10 electrolysis of water The Hoffman apparatus for electrolysis of water.
5E20.10 electrolysis The standard commercial electrolysis apparatus.
5E20.11 electrolysis of water modification Place Tygon tubing over the wire coming out the bottom to protect it from the acid.
5E20.12 electrolysis of water A projection electrolytic cell for showing the evolution of gas.
5E20.15 explosion of hydrogen and oxygen Make soap bubbles with the gases from electrolysis of water and blow them to droplets.
5E20.21 phenolphthalein electrolysis indicat Phenophthalein is used as an indicator in electrolysis demonstrations.
5E20.22 purple cabbage electrolysis indicato Use purple cabbage as an indicator for electrolysis demonstrations.
5E20.22 electrolysis of sodium sulfate with Use purple cabbage as an indicator to show electrolysis of sodium sulfate.
5E20.25 electrolysis of Na ions through glas Sodium is plated on the inside of a lamp inserted into molten sodium nitrate.
5E20.28 mass transfer in electrolysis Measure the current while transferring mass by plating copper to obtain a semi quantitative determination of the Faraday.
5E20.29 mass of Na atom by electrolysis A method of determining the mass of a sodium atom by electrolysis.
5E20.30 electrolytic rectifier Electrodes of aluminum and lead in a saturated solution of sodium bicarbonate form a rectifier.
5E20.40 oxidation of ferrous to ferric iron Put ferrous iron in hot water with nitric acid and heat.
5E20.60 electric forge Melt an iron rod cathode in a strong sodium sulfite solution.

30. Plating

5E30.10 copper flashing of iron
5E30.10 copper flashing of iron Polished iron is plated in a copper sulfate solution.
5E30.20 electroplating copper
5E30.20 electroplating copper Copper and carbon electrodes in a copper sulfate bath.
5E30.20 electroplating Copper is plated onto a carbon electrode in a copper sulfate bath.
5E30.24 electroplating - lead tree Current is passed between lead electrodes in a saturated solution of lead acetate causing fern like clusters to form on the cathode.
5E30.26 electroplating - tin tree Current is passed between electrodes of copper and tin in a acid solution of stannic chloride. With copper as the cathode, tin crystallizes as long needles.
5E30.28 electroplating Plate with copper or silver by connecting the object to the negative terminal and using copper sulfate or silver nitrate solution.
5E30.30 pickle frying Apply high voltage across a pickle and it lights at one end.
5E30.40 silver coulomb meter
5E30.40 silver coulombmeter Silver is plated in a silver nitrate bath onto a platinum cup.
5E30.40 silver coulombmeter A silver coulombmeter shows a 1 g change in anode weight when 1 amp is passed for 1000 sec.

40. Cells and Batteries

5E40.01 Volta's EMF concept The distinction between EMF and electrostatic potential difference is discussed.
5E40.05 contact potentials: history, etc The history, concepts, and persistent misconceptions on the contact potentials between metals.
5E40.10 EMF dependence on electrode material
5E40.10 EMF dependence on electrode material
5E40.10 dependence of EMF on electrode mater Two stands each hold several strips of different metals which can be paired and dipped into a dilute acid bath.
5E40.10 battery effect Combinations of copper, lead, zinc, and iron are dipped into a dilute sulfuric acid solution.
5E40.15 contact potential difference The contact potential difference between copper and zinc can be demonstrated using a condensing electroscope.
5E40.20 voltaic cell
5E40.20 voltaic cell A voltaic cell is made with copper and zinc electrodes in a sulfuric acid solution.
5E40.20 voltaic cells Short a few voltaic cells in series through a loop of iron or nichrome wire.
5E40.21 cardboard model voltaic cell circuit A cardboard model illustrates potential difference and electromotive force in a voltaic cell circuit.
5E40.25 lemon battery/voltaic cell
5E40.25 lemon battery/voltaic cell Stick copper and galvanized steel electrodes into a lemon and attach a voltmeter.
5E40.25 lemon screamer,lasagna cell A little tutorial on electrochemistry for those using the lemon screamer and other interesting cells.
5E40.25 lemon battery Zinc and copper strips are hooked to a galvanometer and stuck into fruits and vegetables.
5E40.26 voltaic cell polarization Heat the copper cathode in a Bunsen burner flame to oxidize the surface.
5E40.40 Crowsfoot or gravity cell A zinc-zinc sulfate/copper-copper sulfate battery.
5E40.50 adding dry cells Charge an electroscope with a number of 45 V B batteries in series.
5E40.51 dry cell terminals Hook up several dry cells in series to a condensing electroscope, remove the capacitance and test polarity with charged rods.
5E40.60 lead acid simple battery
5E40.60 lead acid simple battery A simple lead acid battery with two electrodes is charged for a short time and discharged through a bell.
5E40.60 storage battery Two lead plates in a sulfuric acid solution are charged and then discharged through a doorbell.
5E40.60 storage cells The elementary lead storage cell is charged and discharged on the lecture table.
5E40.60 simple battery Charge two lead plates in 30% sulfuric acid and discharge through a flashlight bulb.
5E40.61 storage cells Melt nail with a storage battery.
5E40.62 lead-salt cell Instead of acid, use a saturated salt solution of sodium bicarbonate and magnesium sulfate.
5E40.70 internal resistance of batteries
5E40.70 internal resistance of batteries
5E40.75 weak and good battery
5E40.75 internal resistance of batteries Measure similar no load voltage on identical looking batteries and then apply a load to each and show the difference in voltage between a good and weak battery.

50. Thermoelectricity

5E50.10 thermocouple Two iron-copper junctions, one in ice and the other in a flame, are connected to a galvanometer.
5E50.10 thermocouple Attach a voltmeter to the iron wires of two copper-iron junctions while they are differentially heated.
5E50.10 thermocouple Two iron-copper junctions, one in ice and the other in a flame, are connected to a galvanometer.
5E50.10 thermocouple Place a twisted wire thermocouple in a flame and observe the current on a lecture table galvanometer.
5E50.11 thermocouples Heating two metals causes a deflection on a galvanometer.
5E50.12 thermoelectric generator Review of a commercial thermoelectric generator made from 150 constantan/nickel-molybdenum thermocouples in series.
5E50.15 Seebeck effect The thermoelectric effect of copper-iron junctions.
5E50.17 Seebeck and Peltier effects Send current through a copper-iron-copper circuit for several seconds and immediately disconnect and switch to a galvanometer.
5E50.18 copper-iron junctions ring Sixty copper-iron junctions in series are arrayed in a ring heated simultaneously with a Bunsen burner producing 90 mA.
5E50.19 thermoelectric compass Bars of copper and iron are joined to form a case for a compass needle. The needle will indicate the direction of the current as one or the other junction is heated.
5E50.19 thermocouple coil magnet Heat a thermocouple loop and the current produces a magnetic field that can be detected by a compass needle.
5E50.20 thermoelectric effect in a wire Show that a piece of soft iron wire connected to a galvanometer has little thermoelectric effect until the wire is kinked.
5E50.25 Thompson effect A flame moved along a long wire will "push ahead" current.
5E50.30 thermoelectric magnet
5E50.30 thermoelectric magnet Heat one side of a heavy copper loop closed by an unknown metal to generate thermoelectricity for an electromagnet.
5E50.30 thermoelectric magnet A ring of copper shorted by iron forms a thermocouple that powers an electromagnet when one end is in water and the other is heated in a flame.
5E50.30 thermoelectric magnet One end of a heavy copper bar bent into a loop and closed with a copper-nickel alloy is heated, the other cooled. An electromagnet made with a soft iron shell can support 200 lbs. Picture.
5E50.30 thermocouple magnet A Bunsen burner heats one side of a thermocouple magnet supporting over 10 Kg.
5E50.30 thermoelectric magnet Heat and cool opposite sides of a large thermocouple. Suspend a large weight from an electromagnet powered by the thermocouple current.
5E50.36 3M Aztec lamp A thermocouple is built into a kerosene lamp.
5E50.60 Peltier effect
5E50.60 thermoelectric cooler A Peltier device is used to cool a drop of water.
5E50.60 thermoelectric heat pump Mount aluminum blocks with digital thermometers on either side of a Peltier device. Run the current both ways.
5E50.61 Peltier effect Directions for making an antimony-bismuth junction and an apparatus to show heating and cooling.
5E50.62 Peltier effect Directions for building a Peltier effect device.
5E50.90 pyroelectric crystals Demonstrate the temperature effect on the polarization of pyroelectric crystals. Picture.
5E50.93 domains of electric polarization Tiny BaTiO3 crystals are heated on a microscope slide until the domains disappear.

60. Piezoelectricity

5E60.05 piezoelectric model A ball and spring model of the piezoelectric effect.
5E60.10 quartz crystal scraped
5E60.12 Rochelle salt demos Ferroelectricity, hysteresis, Curie-point, and the direct piezoelectric effect are demonstrated with a Rochelle salt. Diagrams, Construction and Preparation details in appendix, p.1322.
5E60.13 piezoelectric effect - Rochelle salt A Rochelle salt is hooked to a neon lamp or electrostatic voltmeter.
5E60.15 piezoelectric sheets Make sheets of polycrystalline Rochelle salt that show piezoelectric effects.
5E60.16 PZT sources Two sources for ceramic lead-zirconate-titnante (PZT), 1961.
5E60.20 piezoelectric sparker
5E60.20 piezoelectric sparker Attach the commercial piezoelectric sparker to Braun electroscope.
5E60.21 piezoelectric gas lighter modified Mount a sphere on the end of a piezoelectric gas lighter.
5E60.25 piezoelectric gun
5E60.25 piezoelectric gun A piezoelectric gun is used to discharge a set of charged nylon strings.
5E60.25 piezoelectric pistol One end of a piezoelectric crystal is attached to a needle point in the pistol.
5E60.30 stress vs. voltage
5E60.30 stress vs. voltage Measure the voltage of a Swignette salt crystal under various stresses produced by a mass on a lever arm.
5E60.40 piezoelectric speaker
5E60.40 piezoelectric speaker Excite a Seignette salt crystal with an audio voltage and couple it to a sounding board.
5E60.41 converse piezoelectric effect Connect an audio oscillator to a large Rochelle salt crystal and the sound can be distinctly heard.
5E60.42 piezoelectric speaker Apply an audio oscillator to a Rochelle salt and amplify with a wood sounding board.
5E60.45 resonating capacitor A HYK capacitor (containing BaTiO3) resonates mechanically at a number of frequencies in the audio range.
5E60.47 piezoelectric oscillator Four Rochelle salt crystals are mounted at the center of a long square cross section steel bar and driven by a circuit. Circuit diagrams.
5E60.60 hysteresis in barium titanate A circuit for showing hysteresis in ferroelectric crystals on the oscilloscope.


10. Ohm's Law

5F10.05 charge density in circuits Two demonstrations: first, an electroscope is used to probe the charge density along a large resistance attached to a 5 KV supply, and second, an example where current is flowing through a resistance with no change in potential.
5F10.10 Ohm's law Measure current and voltage in a simple circuit. Change the voltage or resistance.
5F10.10 Ohm's Law An ammeter, voltmeter, rheostat, and battery pack are connected to demonstrate Ohm's law.
5F10.10 Ohm's law A battery, rheostat, and meters in a circuit.
5F10.10 Ohm's law Measure current and voltage in a simple circuit.
5F10.10 Ohm's law Place 2, 4, and 6 V across a resistor and measure the current, then graph.
5F10.12 water analogy circuit A water analogy illustrates voltage drops across a dc circuit.
5F10.15 water Ohm's law analog
5F10.15 water analog A water analog of Ohm's law.
5F10.15 IR drop in a wire Clip wires from the terminals of flashlight lamps at various points along a stretched wire carrying 2 - 5 amps.
5F10.20 potential drop along a wire
5F10.20 potential drop along a wire Lecture galvanometers configured as a voltmeter and ammeter measure current and voltage on several samples of wire of the same length. A slide clip can be used to vary length.
5F10.20 voltage drop along wire Measure the voltage at six points on a long resistance wire.
5F10.25 potential drop with Wimshurst
5F10.25 potential drop with static machine A 3 m long wood bar is attached at one end to one terminal of a static machine. The other end can be grounded or insulated. Attach several electroscopes along the bar to show flow of charge and potential drop.
5F10.26 high voltage Ohm's law Two ends of a dry stick are attached to a static machine. Measure with an electrostatic voltmeter and microammeter.

15. Power and Energy

5F15.10 electrical equalivanet of heat
5F15.10 electrical equivalent of heat Measure the voltage and current to a heating coil in a calorimeter.
5F15.10 heat and electrical energy A heating coil in a calorimeter.
5F15.10 electrical equvalent of heat Voltage, current to a heater and temperature rise in water are measured.
5F15.10 electrocalorimeter Determine the power delivered by temperature change in water and compare to that computed from voltage, current, and time.
5F15.11 flow calorimeter Water is heated electrically as it flows through a tube.
5F15.12 heating by current from a static mot The ends of a piece of wood sealed in a glass tube are attached to a static machine. The half watt dissipated heats the air and an attached manometer measures the volume change.
5F15.15 KWH meter and loads Measure the power consumed by an assortment of household appliances.
5F15.16 heating with current Large currents are passed through No. 18 nichrome wire and the volts and amps are measured.
5F15.17 heating wires in series Several lengths of different wires of the same length are soldered together in series and a piece of paper is hung from each by soft wax. As current is passed through the wire, the paper falls off at different times.
5F15.20 hot dog cooker
5F15.20 hot dog/pickle cooker
5F15.20 hot dog cooker Hook nails to 110V and place them on and then in a hot dog.
5F15.20 hot dog frying Apply 110 V through a hot dog and cook it.
5F15.30 fuse with 30v lamp
5F15.31 fuse-wire problem With fuse wires of different diameters connected in parallel, which will burn out first?
5F15.32 vaporize wire with 500 amp surge Short a low voltage high current transformer with zinc coated iron wire.
5F15.33 fuse wire Fuse wire is used with a miniature house circuit.
5F15.34 fuses Fuse wire of different sizes are connected across a heavy copper buss.
5F15.35 fuse with increasing load
5F15.40 voltage drops in house wires
5F15.40 voltage drops in house wires Two resistance wires substituting for house wiring glow when they power a load of lamps and heaters.
5F15.45 IR2 losses
5F15.45 I2R losses Copper and nichrome wires in series show different amounts of heating due to current. A paper rider on the nichrome wire burns.

20. Circuit Analysis

5F20.10 Kirchoff's voltage law Measure the voltages around a three resistor and battery circuit.
5F20.10 Kirchoff's voltage law Same as Eo-2.
5F20.10 Kirchoff's voltage law Measure the voltages around a three resistor and battery circuit.
5F20.10 sum of IR drops Measure the voltages across three resistors and a battery in a series circuit.
5F20.13 voltage divider A simple series circuit of a battery and two resistors.
5F20.15 continuity of current
5F20.15 continuity of current Same as Eo-4.
5F20.15 continuity of current An ammeter can be inserted into any branch of a circuit to show currents in and out of a node.
5F20.16 conservation of current Measure the currents entering and leaving a node.
5F20.20 superposition of current
5F20.20 superposition of current Same as Eo-7.
5F20.20 superposition of currents Measure the current from one battery, a second in another position, and the combination in a circuit.
5F20.20 superposition Shows a standard superposition circuit.
5F20.25 reciprocity
5F20.25 reciprocity Shows a standard reciprocity circuit.
5F20.30 potentiometer
5F20.30 potentiometer A slide wire potentiometer is used with a battery and demonstration galvanometer.
5F20.30 potentiometer A slide wire potentiometer with a standard cell.
5F20.31 rheostat as potential divider Contrast the slide wire rheostat when used as a rheostat or potential divider.
5F20.32 long potentiometer Use a ten foot length of nichrome wire as a slide wire potentiometer.
5F20.33 rheostat potential divider A rheostat and six volt battery demonstrate a potential divider.
5F20.40 Wheatstone bridge
5F20.40 wheatstone bridge - slide wire The slide wire Wheatstone bridge.
5F20.40 wheatstone bridge - slide wire Two nichrome wires are stretched across the lecture bench and sliding clips connected to a galvanometer are used to find equal potential points.
5F20.41 wheatstone bridge - human galvan. Stretch a loop of close line previously soaked in salt solution in a parallelogram and hook the ends to a 110 V line. Touch two points of the same potential without shock.
5F20.42 wheatstone bridge A demonstration Wheatstone bridge with a built in meter and several plug in resistors.
5F20.45 light bulb Wheatstone bridge
5F20.45 lightbulb wheatstone bridge A Wheatstone bridge configuration with lightbulbs for resistors.
5F20.45 light bulb wheatstone bridge Four light bulbs in a Wheatstone bridge arrangement with light bulb indicator.
5F20.45 light bulb wheatstone bridge A light bulb Wheatstone bridge using 110 ac.
5F20.45 wheatstone bridge Four 60 W lamps in a diamond bridge with a 10 W lamp as the indicator. An additional 6 V lamp can be switched in when the circuit is balanced.
5F20.45 wheatstone bridge Three 110 V lamps and a rheostat make up the diamond of a Wheatstone bridge and a small lamp serves as an indicator.
5F20.50 series and parallel light bulbs A light bulb board with switches allows configuration of several combinations of series and parallel lamps.
5F20.50 series and parallel light bulbs
5F20.50 series and parallel light bulbs A light bulb board with switches allows configuration of several combinations.
5F20.50 parallel and series light bulbs Three similar wattage lamps in series, three in parallel.
5F20.50 series-parallel circuits A series-parallel circuit with three bulbs and six switches can be connected 14 ways.
5F20.50 series/parallel light bulbs Three 110 V lamps are wired in series and three are wired in parallel.
5F20.51 light bulb board - 12 V
5F20.51 light bulb board - 12 V A board with 12V bulbs and a car battery allow combinations of up to three series or three parallel loads.
5F20.55 series and parallel resistors
5F20.55 series/parallel resistors Measure the current flowing through a wire resistor with 6 V applied and then series and parallel combinations.
5F20.56 wire combinations A wire circuit is arranged so a segment of n length can have 1 or n wires in parallel. Drawing.
5F20.60 equalivanet resistance
5F20.60 equivalent series resistance A series of resistors in a circuit are replaced by a single resistor.
5F20.61 parallel resistance - integral value A formula for obtaining integral values of resistors in parallel to obtain an integral equivalent resistance.
5F20.61 equivalent parallel resistance Parallel resistors are replaced by a single resistor in a circuit.
5F20.63 Thevenin's equivalent resistance A Wheatstone bridge resistance circuit is used to reduce resistor combinations to an equivalent resistance.
5F20.64 equivalent circuit flasher A neon flasher circuit shows the combination rules for series and parallel combinations of resistance and capacitance by timing light flashes.
5F20.71 large circuit boards A modular circuit board made for 500 student auditoriums.
5F20.72 general circuits board A circuit board laid out so meters can be plugged in and readings taken for demonstrations of series-parallel circuits and Kirchhoff's laws.
5F20.75 three-way switch A large circuit board demonstrates a three way switch.
5F20.79 one boar, river, six people An electrical circuit for solving the problem of getting across the river.
5F20.95 equivalent resistance analog comput. Using the equivalent resistance of a circuit as an analog computer for finding the focal length of an optical problem.

30. RC Circuits

5F30.10 capacitor and light bulb A large lelectrolytic capacitor, a light bulb, and a 120 V dc supply in series show a long time constant.
5F30.10 capacitor and light bulb A 5600 microF capacitor is charged and discharged through 7.5 and 40 W light bulbs.
5F30.10 long RC time constant A 5600 microF capacitor, a light bulb, and a 120 V dc supply in series show a long time constant where the bulb dims as the capacitor charges.
5F30.11 light the bulb Charge a capacitor with DC and discharge through a light bulb, try the same thing with AC.
5F30.12 discharge a capacitor Discharge a capacitor through a resistor. Read the voltage with a meter.
5F30.15 RC time constant on galvanometer
5F30.15 RC time constant on galvanometer A series RC circuit with a galvanometer. Diagram.
5F30.16 RC voltage follower Use a voltage follower to isolate the circuit from the display.
5F30.20 RC time constant on scope
5F30.20 RC time constant on scope A circuit with a slow time constant (.1 - 10 sec.) is charged and discharged and the current and voltage are displayed on a dual trace storage scope.
5F30.20 RC charging curve Show charging and discharging a RC circuit with a battery on an oscilloscope.
5F30.21 RC time constant Show the time constant from an RC circuit on an oscilloscope.
5F30.21 RC time constant A plug in circuit board for showing RC time constants on the oscilloscope.
5F30.22 time constant of an capacitive cir. The time constant of a RC circuit driven by the calibration signal is shown on an oscilloscope.
5F30.28 finding R from time constant A circuit to measure high resistances by using an RC charging time.
5F30.50 series and parallel capacitors
5F30.50 series and parallel capacitors Two 2 microF capacitors in series or parallel with a 40 W lamp.
5F30.60 neon relaxation oscillator
5F30.60 blinking neon bulb A neon bulb in parallel with a capacitor will light periodically as the capacitor charges and discharges.
5F30.60 RC relaxation oscillator An RC relaxation oscillator has a neon lamp across the capacitor provide a visible discharge.
5F30.60 RC flasher circuit A neon lamp in parallel with the capacitor in a series RC circuit.
5F30.60 flashing neon light A battery powered neon light oscillator.
5F30.60 neon relaxation oscillator A circuit for a neon relaxation oscillation oscillator. Reference: AJP 13(12),415.
5F30.60 relaxation oscillator An RC neon light relaxation oscillator.
5F30.61 relaxation siren oscillator A double RC relaxation oscillator with slow and fast periods gives a siren waveform.
5F30.68 backward and forward waves RC circuits are used to get a wave in neon bulbs that goes from the sink to the source.
5F30.71 capacitance operated relay References but no information on the circuit. Bring your hand close to a aluminum plate and the relay triggers.
5F30.80 fun circuit One box has switches that control two lights in another box but only one wire connects the two boxes.

40. Instruments

5F40.10 sensitivity and resistivity of a galv.
5F40.10 sensitivity and resistance of a galv A circuit for the determination of galvanometric constants.
5F40.10 sensitivity and resistance of galvan Use external resistors to measure the resistance and sensitivity of a galvanometer.
5F40.15 voltmeter and electroscope Connect series resistance to a galvanometer to make a voltmeter with low sensitivity and measure several dry batteries in series with both the voltmeter and an electroscope.
5F40.20 galv. as ammeter and voltmeter
5F40.20 converting a galvanometer to a voltm Knowing the resistance and sensitivity of a galvanometer, add a series resistance and check with a voltage.
5F40.20 galvanometer as voltmeter and ammete A galvanometer is used with shunt and series resistors.
5F40.21 loading by voltmeter
5F40.21 loading by a voltmeter Measure the voltage across a high resistance circuit with high and low impedance voltmeters.
5F40.25 converting a galvanometer to a ammet Knowing the resistance and sensitivity of a galvanometer, add a shunt resistance and measure a current.
5F40.30 hot wire ammeter A crude hot wire galvanometer.
5F40.30 hot wire ammeter Diagram of a hot wire ammeter. (E-171).
5F40.35 iron vane meter Repulsion from induced magnetism in two soft iron bars in a solenoid forms the basis of a heavy current ammeter.
5F40.50 multimeters A couple multimeters are pictured.


10. Magnets

5G10.10 magnet assortment
5G10.10 magnet assortment
5G10.13 letters on magnets Remarkably. the letters on the magnet are two the the three that can be read from either end or in a mirror.
5G10.14 various magnets Various magnets are pictured.
5G10.14 strong magnets Various strong magnets are shown.
5G10.15 lodestone
5G10.15 lodestone Show that the lodestone attracts small nails.
5G10.16 lodestone suspended
5G10.16 lodestone Magnetite is suspended in a magnetic field.
5G10.16 permanent magnets Pick up nails with a cobalt steel magnet. Also - levitation, elastic collisions.
5G10.16 lodestone Two pieces of magnetite in paper stirrups come to rest on the magnetic meridian. Poles are identified and repulsion and attraction are demonstrated.
5G10.16 lodestone A large lodestone is suspended in a cradle with the south pole painted white. A bar magnet is used to show attraction and repulsion.
5G10.20 break a magnet
5G10.20 break a magnet Show a magnet attracts nails, break it and repeat.
5G10.20 forming new magnetic poles Break a magnet.
5G10.20 break a magnet Magnets of hard or hardened steel are broken and the pieces shown to be magnetized.
5G10.20 broken magnet A broken magnet still exhibits north and south poles.
5G10.30 Which is a magnet?
5G10.30 magnet and non-magnet Two bars look alike, one is a magnet and the other is not.
5G10.30 Which is a magnet? With two similar bars of iron, one magnetized, use the end of one to lift the middle of the other.
5G10.35 two south pole magnet How to induce four poles in a knitting needle, the same poles at each end.
5G10.36 no pole magnet Make a circularly polarized magnet in a steel ring and then break it in half.
5G10.50 lowest energy configuration of magnets
5G10.50 magnetic interactions Magnets float in water with the north pole up constrained by a ring magnet. Place up to 22 magnets in the tub and show equilibrium configurations.
5G10.50 lowest energy configuration Magnets held vertically in corks are placed in a dish of water. When a coil around the dish is energized, the magnets move to the lowest energy configuration.
5G10.90 cast magnetic field Iron filings are cast in gelatin.
5G10.90 magnetic monopole Iron filings cast in acrylic over one pole of a magnet.
5G10.90 isolated pole An "isolated pole" is demonstrated by passing a long magnetized knitting needle through a cork and floating it on water.

20. Magnet Domains & Magnetization

5G20.10 Barkhausen effect
5G20.10 Barkhausen effect Amplify the signal from a small coil as it is flipped in a magnetic field with copper, soft iron, and steel cores.
5G20.10 Barkhausen effect Magnetic domains in the core of a small coil can be heard flipping as a magnet is moved by using and an audio amplifier.
5G20.10 Barkhausen effect Insert various cores into a coil connected to an audio amplifier and spin a magnet around it.
5G20.10 Barkhausen effect Stretch a iron-nickel alloy wire through a coil and bring a magnet close to demonstrate sudden simultaneous magnetization.
5G20.10 Barkhausen effect Soft iron and hard steel cores are placed in a small coil attached to an audio amplifier and the assembly is inserted into a magnetic field.
5G20.10 Barkhausen effect A soft iron core inserted in a small coil connected to the input of an audio amplifier.
5G20.10 Barkhausen effect Pulses from moving a magnet near a coil wrapped around a soft iron core are amplified.
5G20.15 spin-flop transition model A mechanical model of the spin-flip transition in antiferromagnets.
5G20.20 ferro-optical garnet
5G20.20 ferro-optical garnet View a commercial ferro-optical garnet between crossed Polaroids with a color TV on a microscope as the field in the coil is changed.
5G20.21 ferromagnetic garnet Examine a crystal of M3Fe2(FeO4)3 in a polarizing microscope. Diagrams, Reference: AJP,27(3),201.
5G20.22 Weiss domains Examine a Gadolinium-Iron-Garnet crystal in a polarizing microscope as the magnetic field and temperature are changed. Picture, Reference: AJP,27(3),201.
5G20.23 optical ferromagnetic domains Examine thin polished crystals under a low powered microscope in polarized light. Add a small coil to change the field.
5G20.27 iron filing domains A tube of compressed iron filings is magnetized and then the iron filings are agitated.
5G20.30 magnetic domain model An array of small compass needles shows domain structures.
5G20.30 magnetic domains An array of small compass needles shows domain structures.
5G20.30 magnetic domain model A set of compass needles on pins.
5G20.31 compass arrays
5G20.31 compass array An array of compass needles made of spring steel strip stock shows domains under different magnetic field conditions.
5G20.31 compass array A set of magnetic needles on pivots orients randomly until a magnet is brought close. Barkhausen model - A compass array above an electromagnet will show that the needles align discontinuously as the field is increased.
5G20.36 Heisenberg anitferromagnet model A simple mechanical model demonstrates phase transitions in a Heisenberg antiferromagnet.
5G20.45 induced magnetic poles
5G20.45 induced magnetic poles A chain of nails is supported by a magnet, each becoming a magnet by induction.
5G20.46 magnetic induction A soft iron bar held colinear with a permanent magnet will become magnetized by induction. Use a compass needle to show the far pole of the bar is the same as the near pole of the magnet.
5G20.50 pound iron bar
5G20.50 pound iron bar
5G20.50 magnetization in the earth's field Hammer the end of a soft iron bar in the earth's magnetic field.
5G20.50 pound iron bar Pound a soft iron bar held in the earth's field, a permalloy bar does not need to be pounded.
5G20.50 hammer an iron bar Hammer a soft iron bar held parallel to the field of the earth. A bar of permalloy is magnetized by simply holding it in the earth's field.
5G20.50 magnetic induction in earth's field Hammer the end of a soft iron rod held parallel to the earth's field. Hold a permalloy rod parallel while picking up pieces of permalloy ribbon, then turn perpendicular.
5G20.55 permalloy bar
5G20.55 permalloy bar
5G20.55 permalloy bar Iron filings stick to a permalloy bar held parallel to the earth's magnetic field but fall off when it is held perpendicular.
5G20.55 permalloy in earth's field A small strip of iron sticks to a permalloy rod when it is held in the direction of the Earth's field.
5G20.56 permalloy rod Hold a permalloy rod near a compass needle.
5G20.60 magnetization by current
5G20.60 magnetization and demagnetization Place an iron core in a solenoid. Magnetize with direct current and demagnetize by reducing alternating current to zero.
5G20.60 magnetization by current Place a piece of steel in a solenoid connected to a direct current source.
5G20.60 magnetizing iron Place an iron bar in a solenoid and pulse a large current.
5G20.61 magnetization by contact
5G20.61 magnitizing iron by contact Stroke a nail on a permanent magnet and it will pick up iron filings.
5G20.62 demagnitization by hammering
5G20.62 magnetization and demagnetization Stroke a steel needle with a permanent magnet to magnetize and pass it through an AC solenoid to demagnetize.
5G20.62 demagnitizing iron by hammering Magnetize an iron bar in a solenoid, then pound it to demagnetize.
5G20.70 electromagnet - lift person
5G20.70 electromagnet A simple electromagnet.
5G20.70 electromagnet with 1.5 V battery A magnet powered by a 1.5 V battery lifts a large weight.
5G20.71 electromagnet
5G20.71 electromagnet
5G20.71 electromagnet An electromagnet with 25 turns of wire and one dry cell can lift over 200 lbs.
5G20.72 large electromagnet
5G20.72 magnet holding with small battery An electromagnet energized with a small battery holds several Kg.
5G20.72 large electromagnet This magnet is made with 3000 turns and carries 25 amps.
5G20.73 magnetic circuit An iron loop with a coil on one side, a flux meter on the other, and a removable section for substituting various materials.
5G20.73 measuring magnetic flux Measure magnetic flux with and without a iron path. Not a good description.
5G20.74 large electromagnet Apparatus Drawings Project No. 13: A simple low cost electromagnet with 4"x4" pole faces, field of 1 weber/m2 with a .5 cm gap.
5G20.75 retentivity
5G20.75 retentivity
5G20.75 retentivity Two soft iron cores form a split toroid with a few turns of wire around one half. When the coil is energized the iron is strongly magnetized. When the current is off, the two pieces are still difficult to separate but once apart no longer attract.
5G20.75 retentivity A soft iron bar will cling to a "U" shaped electromagnet when the current is turned off but no longer attract after it is pulled away.
5G20.76 different cores An electromagnet is made with replaceable yoke to show the effect of different materials on lifting strength.

30. Paramagnetism and Diamagnetism

5G30.10 paramagnetism and diamagnetism
5G30.10 paramagnetism and diamagnetism Paramagnetic and diamagnetic crystals are inserted between the poles of a large electromagnet.
5G30.11 paramagnetism and diamagnetism Small samples of bismuth, aluminum, glass, etc between the poles of a strong electromagnet with an inhomogeneous magnetic field. Picture.
5G30.13 paramagnetic and ferromagnetic A small sphere of Pyrothit suspended near one pole of a horseshoe magnet will show paramagnetic and ferromagnetic behavior in different orientations.
5G30.15 pull the sample
5G30.15 John Davis setup
5G30.15 paramagnetism and diamagnetism Samples of bismuth and copper sulfate are suspended by threads. A large horseshoe magnet attracts the copper sulfate and repels the bismuth.
5G30.16 dollar bill attraction A dollar bill is attracted by a magnet.
5G30.16 para. and diamagnetism in a level Pull the bubble in a carpenter's level with a magnet. Also, pull liquid air drops around on a sheet of paper.
5G30.17 pole faces for big electromagnet Apparatus Drawings Project No. 29: Large electromagnet accessories, one of four. Plans for pole faces to go on the electromagnet from No. 13 for use in para and diamagnetism demonstrations.
5G30.18 paramagnetism and diamagnetism Specifications are given for building an electromagnet suitable for the demonstration. Paramagnetic and diamagnetic substances are listed.
5G30.20 paramagnetism of liquid oxygen
5G30.20 paramagnetism of liquid oxygen Liquid oxygen sticks to the pole pieces of a strong electromagnet until it evaporates.
5G30.21 paramagnetism A test tube of liquid oxygen swings into the gap of an electromagnet.
5G30.25 paramagnetism Copper sulfate and bismuth crystals are suspended in a magnetic field.
5G30.25 paramagnetism of bismuth A bismuth crystal is suspended between the poles of an electromagnet.
5G30.30 para and dia in para and dia solutio A paramagnetic body is suspended in a paramagnetic solution. Repeat same with diamagnetic.

40. Hysteresis

5G40.10 hysteresis loop on scope
5G40.10 hysteresis loop on scope Show the hysteresis loops for laminated steel and ferrite cores as saturation is reached.
5G40.10 hysteresis loop The hysteresis loop of a core is displayed on an oscilloscope.
5G40.10 hysteresis curve The Leybold setup shown on a scope.
5G40.11 hysteresis loop on scope The hysteresis loop for the iron core of a transformer is shown on a oscilloscope. Diagram and circuit hints.
5G40.12 hysteresis on the scope A circuit for showing the hysteresis curve of a transformer on an oscilloscope. Also modifications for using various cores and coils.
5G40.13 improved hysteresis loop on scope A circuit, Hall probe, and storage oscilloscope allow plotting the hysteresis loop point by point or automatically.
5G40.14 hysteresis without induction Two coils are mounted on a rotating disk in the air gap of an electromagnet. As the field is varied, the hysteresis loop is plotted.
5G40.15 hysteresis loop This circuit makes it possible to display hysteresis loops of inductors with only one winding.
5G40.16 hysteresis on x-y An op amp circuit for plotting the hysteresis curve slowly on an x-y recorder.
5G40.20 magnetization and hysteresis A small mirror on a compass needle is used to detect the magnetic field as the current to a solenoid containing an iron bar is increased and decreased stepwise.
5G40.21 simple hysteresis Parallel iron bars suspended in a coil show hysteresis when slowly magnetized and demagnetized.
5G40.25 hysteresis plot A ballistic galvanometer search coil gives readings of the magnetization and residual magnetization of a sample as it is magnetized in opposite directions and a plot is generated.
5G40.27 plotting hysteresis A core with a removable link and built in flux meter are used to plot a hysteresis curve.
5G40.31 hysteresis in a motor The I V curve from a generator is proportional to the normally obtained B H curve.
5G40.41 hysteresis loop with old tv The hysteresis loop of a sample placed in one deflection coil is traced on an old TV tube.
5G40.50 hysteresis waste heat
5G40.50 hysteresis waste heat Water is boiled by magnetic hysteresis waste heat.

45. Magnetostriction and Magnetores

5G45.10 magnetostrictive resonance
5G45.10 magnetostrictive resonance Drive a nickel rod by a coil at one end at a frequency that corresponds to a natural harmonic of sound waves.
5G45.20 magnetostrictive Newton's rings One end of a ferromagnetic rod in a coil touches one plate of a Newton's rings apparatus.
5G45.30 magnetostriction of nickel wire
5G45.30 magnetostriction of nickel wire An optical lever arrangement shows magnetostriction of nickel wire.
5G45.31 magnetostriction Nickel constricts and cobalt steel lengthens when magnetized. Place sample rods in a solenoid and show the effect by optical lever.
5G45.35 inverse magnetostrictive effect The inverse magnetostrictive effect in nickel wire.
5G45.40 delta E effect The magnetostrictive resonance is measured with and without an external field.
5G45.60 Bi-spiral The magnetoresistance of a Bi-spiral in a magnetic field. Picture.
5G45.70 magnetoresistance
5G45.70 magnetoresistance Measure the magnetoresistance of a bismuth spiral placed in a large electromagnet.
5G45.80 corbino disk A corbino disk (InSb) in one arm of a Wheatstone bridge is placed in a large electromagnet.

50. Temperature and Magnetism

5G50.10 Curie point
5G50.10 Curie point Iron under magnetic attraction is heated until it falls away. Upon cooling it is again attracted.
5G50.10 Curie temperature A counterweighted iron wire is attracted to a magnet until heated red with a flame.
5G50.11 Curie point A long soft iron wire held up by a magnet falls off when the wire is heated past the Curie point.
5G50.11 Curie Point A length of soft iron wire heated with 110 V DC through a rheostat shows loss of magnetic properties when it passes through recalescence.
5G50.12 Curie point A pendulum bob with iron wire tips is attracted to a magnet where it is heated until it loses its magnetism and falls away. The cycle repeats. Picture, Diagram.
5G50.13 Curie point with monel metal Monel metals have curie points between 25 C and 100 C depending on the alloy.
5G50.14 Curie temperature A nickel wire falls away from a magnet when heated.
5G50.15 Curie nickel
5G50.15 Curie point of nickel A rod of nickel is attracted to a magnet when cool but swings away when heated. Many hints and diagram.
5G50.15 Curie Nickel A Canadian nickel is attracted to a magnet until it is heated with a torch.
5G50.16 nickel hysteresis surface Pictures of a 3-D HMT hysteresis surface for nickel.
5G50.20 thermomagnetic motor
5G50.20 thermomagnetic motor Local heating of permalloy tape or nickel rings in a magnetic field will cause rotation. AJP 5(1),40.
5G50.20 Monel wheel The rim of a wheel of Monel tape is placed in the gap of a magnet and heat is applied to one side to make the wheel turn.
5G50.20 magnetic heat motor A thin strip of magnetic alloy around the rim of a well balanced wheel is placed in the gap of a magnet with a light focused on a point just above the magnet. Heating changes the magnetic properties and the wheel rotates.
5G50.20 Curie temperature wheel A rim of nickel on a wheel is heated just above the point where the rim passes through the gap of a magnet.
5G50.22 magnetic heat engine A gadolinium strip forming the rim of a plexiglass wheel is heated and cooled on opposite sides of a magnetic field, and a weight is lifted by the resulting rotation.
5G50.23 Curie temperature motor A soft iron disk heated on an edge turns very slowly when a magnet is oriented correctly.
5G50.24 Curie point engine Use the Curie point engine as a simple demonstration of the Carnot principle.
5G50.25 dysprosium in liquid nitrogen
5G50.25 dysprosium in liquid nitrogen A piece of dysprosium is attracted to a magnet when cooled to liquid nitrogen temperatures but drops away when it warms up.
5G50.30 phase change and susceptibility Heat the long iron wire and watch the sag. A ferrite ring and coil connected to a galvanometer show change in ferromagnetic susceptibility.
5G50.35 hysteresis breakdown at Curie temp. Elaborate apparatus to show hysteresis loop and breakdown at Curie temperature. Picture, Diagrams, Materials list in appendix, p. 1333.
5G50.40 adiabatic demagnetization The temperature of a piece of gadolinium is measured with a thermocouple while it is between the poles of an electromagnet.
5G50.50 Meissner effect Cool a superconductor and a magnet floats over it due to magnetic repulsion.
5G50.50 Meissner effect
5G50.50 superconductors Place a small powerful magnet over a disc of superconducting material cooled to liquid nitrogen temperature.
5G50.51 levitating magnet A long article on levitation over superconductors showing several variations.
5G50.52 Meissner effect Repulsion of the magnet and superconductor hanging from threads. Also, levitation of the magnet over the superconductor.
5G50.53 Meissner effect with a cork and salt A magnet/cork in a vial filled with salt water so the float just sinks is placed over the superconductor.
5G50.55 Meissner effect with liquid He Technique for levitating a magnet over liquid He.
5G50.55 floating magnet demonstration A room temperature magnet is suspended 2 cm above a liquid helium cooled (5l/hr) lead plate in a supercooled container. Students can play with the magnet and feel the force. Discussion of what the Meissner effect really is.
5G50.56 detailed explaination of levitation Theoretical article - a discussion of levitation and other effects using Maxwell's work on eddy currents in thin conducting sheets instead of the London equation.
5G50.58 Meissner oscillator A pivoting needle with magnets on the ends oscillates between two superconducting discs.

10. Magnetic Fields

5H10.10 magnetic paper clip arrow
5H10.11 compass A compass is used to find poles.
5H10.11 compass needles & magnet A large compass needle or dip needle is used as an indicator of magnetic field.
5H10.12 magnetoscope A magnetoscope is constructed by hanging needles from the edge of a small brass disc.
5H10.15 dip needle
5H10.15 dip needle A dip needle is used to show the inclination of the earth's magnetic field.
5H10.15 dip needle Use a dip needle to find the local direction of the earth's field.
5H10.15 dip needle A very large dip needle is shown next to the standard catalog size. Check it out.
5H10.15 dip needle Turn a compass on its side. Animation.
5H10.20 Oersted's effect Explore the field around a long wire with a compass needle.
5H10.20 Oersted's effect Demonstrate Oersted's effect with a compass needle and a long wire carrying a heavy current.
5H10.20 Oersted's effect A compass needle is used to explore the field around a long wire.
5H10.20 Oersted's effect A compass deflects above and below a current carrying wire. ALSO- jumping wire.
5H10.20 Oersted's needle Hold a current carrying wire over a bar magnet on a pivot and the magnet moves perpendicular to the wire.
5H10.22 Oersted's effect on OH Four compass needles are arrayed around a vertical wire running through plexiglass for use on the overhead projector.
5H10.22 Oersted's effect on OH Adapting the Oersted effect to the overhead projector.
5H10.23 Oersted's effect A current of 50 amps is passed through a heavy vertical wire and the field is investigated using a compass needle.
5H10.23 mag field of current thru electrolyt A compass needle detects the magnetic field from 2 amps flowing in an electrolyte.
5H10.25 field independent of conductor type A magnetic field produced current in copper, electrolyte, and a gas discharge tube is detected by a large compass needle.
5H10.25 Oersted's effect A heavy current from a storage cell is passed through a long wire and a compass needle is used to investigate the nearby field. Electrolyte or plasma may be substituted for the wire.
5H10.26 carrying large currents Use flat braided brass cable instead of copper wire to carry large currents.
5H10.30 magnet and iron filings Sprinkle iron filings on a glass sheet placed on top of a bar magnet.
5H10.30 magnet and iron filings on overhead
5H10.30 field of a magnet Iron filings are sprinkled on a sheet of plexiglass over a magnet.
5H10.30 iron filings on the overhead Sprinkle iron filings on a magnet between two glass plates.
5H10.30 magnetic fields around bar magnets Sprinkle iron filings on a glass sheet covering a bar magnet.
5H10.31 particles in oil A suspension of carbonyl nickel powder in silicon oil is used as an indicator of magnetic field.
5H10.31 iron filings in glycerine A sandwich of iron filings in glycerine between two glass plates.
5H10.31 iron filings in glycerin Soft iron bars extend the poles of a permanent magnet into a projection cell with iron filings in a equal mixture of glycerin and alcohol.
5H10.32 iron bars & 83 ton magnet Students gather around a large electromagnet while holding iron bars.
5H10.32 reply to comment Reply to the comment on the health hazards of magnetic fields - Field gradient is 1000 times weaker than exposure that has been studied.
5H10.32 comment On the health hazards of magnetic fields.
5H10.33 iron filings on glass plate stack Make a 3-D view of magnetic fields by sprinkling iron filings on a series of stacked glass plates.
5H10.50 area of contact
5H10.50 area of contact One end of a magnet 1 cm in diameter is truncated to .5 cm. The small end lifts a much larger piece of iron than the large one.
5H10.51 area of contact An electromagnet supports less weight when the face of the ring is against the pole than when the curved edge is. Diagram.
5H10.52 area of contact A soft iron truncated cone will support less weight when the large end is in contact with the face of an electromagnet.
5H10.55 gap and field strength
5H10.55 gap and field strength Vary the gap of a magnet and measure the field with a gaussmeter.
5H10.60 shunting magnetic flux
5H10.60 shunting magnetic flux Pick up a steel ball with a bar magnet, then slide a soft iron bar along the magnet toward the ball until it drops off.
5H10.61 magnetic shielding
5H10.61 magnetic shielding Slide sheets of copper, aluminum, and iron between an electromagnet and an acrylic sheet separating nails from the magnet.
5H10.62 magnetic screening Displace a hanging soft iron bar by attraction to a magnet, then interpose a sheet of iron.
5H10.63 magnetic shielding A test magnet is used to show the shielding properties of a soft iron tube with various magnetic field generators.
5H10.65 magnetic screening
5H10.65 magnetic screening Hold a magnet above a nail attached to the table by a string, then interpose a sheet of iron.
5H10.65 magnetic screening Two horizontal sheets of glass separated by and air space intervene between an electromagnet and collection of nails being held up. Insert a sheet of iron into the space and the nails drop.
5H10.75 Compass in a changing mag field Meiners places this demonstration in the Capacitors and Dielectrics section. (????) A compass is placed in the gap of an electromagnet and the field is reversed at various rates.
5H10.80 sensitive magnetometer Building and operating a sensitive magnetometer.

15. Fields and Currents

5H15.10 iron filings around a wire Iron filings are sprinkled around a vertical wire running through the denter of a pexiglass sheet.
5H15.10 field of wire and iron filings
5H15.10 magnetic field around a wire Iron filings show the field of a wire passing through a sheet of plexiglass.
5H15.10 iron filings around a wire Iron filings are sprinkled around a vertical wire running through plexiglass.
5H15.10 magnetic fields around currents Iron filings around a current carrying wire, loop, coil, and solenoid.
5H15.12 uniform and circular fields Use iron filings to show the resultant of a vertical wire passing through a uniform field.
5H15.13 right hand rule
5H15.13 right hand rule Move a compass around a vertical wire with a current, reverse the current. Animation of the right hand.
5H15.15 Biot-Savart law animation
5H15.15 Biot-Savart law Animation.
5H15.20 parallel wires and iron filings
5H15.20 parallel wires and iron filings
5H15.25 anti-parallel wires and iron filings
5H15.25 anti-parallel wires and iron filings
5H15.40 solenoid and iron filings A solenoid is wound through a peice of plexiglass for use with iron filings on the overhead projector.
5H15.40 solenoid and iron filings
5H15.40 field of a solenoid Iron filings show the field of a solenoid wound through a sheet of plexiglass.
5H15.40 solenoid and iron filings A solenoid is wound through a piece of plexiglass for use with iron filings on the overhead projector.
5H15.41 iron filings in a ziploc bag Seal an iron filing/glycerol mixture in a ziploc bag.
5H15.41 iron filings in glycerin A glass cylinder filled with iron filings in a solution of glycerin and alcohol is inserted into a solenoid.
5H15.43 length of a solenoid A large solenoid is constructed to make it easy to change the spacing of turns and therefore the length. A magnetometer or coil is used to show field strength, Picture, Diagrams.
5H15.45 small coils in a solenoid A no iron magnetism model. An array of small coils is mounted inside a large solenoid. Small springs keep the small coils aligned randomly when no current is applied.
5H15.46 demountable Helmholtz coils On making large square demountable Helmholtz coils.
5H15.46 Helmholtz coils Generation of a large uniform magnetic field by Helmholtz coils.
5H15.47 long solenoid The long solenoid used in the e/m experiment is shown.
5H15.50 field of a toroid Iron filings show the field of a toroid which is wound through a sheet of plexiglass.
5H15.50 torroid and iron filings Same as Ei-11.
5H15.50 field of a toroid Iron filings show the field of a toroid wound through a sheet of plexiglass.
5H15.60 iron filings on the overhead Iron filings in a viscous liquid permit field configurations to be shown. More.
5H15.60 iron filings on the overhead Iron filings are sprinkled on glass plates that have a single wire, parallel wires, and a solenoid passing through holes.
5H15.61 filings in castor oil Small iron filings are sprinkled onto a thin layer of castor oil and a magnetic field is applied.
5H15.65 quantitative field of a coil Apparatus Drawings Project No. 2: A search coil is mounted on a movable arm with provision for reading angle and distance.

20. Forces on Magnets

5H20.10 magnets on a pivot One magnet is placed on a pivot, the other is used to attract or repel the first.
5H20.10 magnets on a pivot A magnet is placed in a cradle. A second magnet is used to attract and repel the first.
5H20.10 interaction between bar magnets Bar magnets on pivots.
5H20.10 magnetic attraction/repulsion One magnet is placed on a pivot, the other is used to attract or repel the first.
5H20.15 snap the lines of force
5H20.15 snap the lines of force
5H20.20 levitation magnets
5H20.20 levitation magnets Two ring magnets are placed on an upright test tube with like poles facing.
5H20.20 levitation of magnetic discs Two disc magnets are suspended with like poles facing on an inverted test tube.
5H20.21 magnetic suspension Two notched bar magnets are held with like poles facing.
5H20.23 centrally levitating magnets
5H20.24 linearly levitating magnets
5H20.30 inverse square law
5H20.30 inverse square law Same as AJP 31(1),60.
5H20.30 inverse square law - magnetism A balance to measure the repulsion of two bar magnets. See AJP 31(1),60.
5H20.30 inverse square law - magnetism A balance is made out of a meter stick with a magnet on one end facing the pole of another similar magnet. Adjust the distance between the magnets and slide the counterbalance along the meter stick until equilibrium is reached.
5H20.30 magnetic balance Use a bar magnet brought near a second bar magnet counterweighted and on a knife edge to roughly verify the inverse square law.
5H20.33 hanging magnets Hang two magnets horizontally and parallel. Use the inverse square law to compute the pole strength from the length of the suspension, the saturation, and mass of the magnets.
5H20.35 inverse square law balance
5H20.35 inverse square law
5H20.35 inverse squared power - magnetism Three simple variations of magnets levitating in a glass tube are used to show a force varying with the inverse of the distance squared.
5H20.40 inverse fourth law - dipoles
5H20.40 inverse fourth power - magnetism Equipment shows the force between two dipoles varies as the inverse fourth power of the separation. Pictures.
5H20.50 inverse seventh law - magnet/iron
5H20.50 inverse seventh power - magnetism Apparatus to show the force between a magnet and a piece of soft iron varies with the inverse seventh of the separation. Diagram, Picture.

25. Magnet/Electromagnet Interact.

5H25.10 magnet in a coil
5H25.10 magnet in a coil
5H25.10 interaction of magnet and coil A solenoid on a pivot and a magnet on a pivot interact.
5H25.10 interaction of flat coil & bar mag. A bar magnet is mounted in a large flat coil.
5H25.10 magnet in a coil The deflection of a compass needle in the center of a large coil placed in the plane of the magnetic meridian is proportional to the tangent of the current.
5H25.10 solenoid bar magnet A suspended solenoid reacts with a bar magnet only when the current is on.
5H25.15 period of a bar magnet A magnet oscillates in a coil proportional to the square of the current in the coil.
5H25.20 jumping magnet
5H25.20 jumping magnet Place a bar magnet in a vertical transformer and apply DC with a tap switch.
5H25.25 force on a solenoid core
5H25.25 force on solenoid core When a solenoid is energized a iron core is violently drawn into the coil.
5H25.30 magnetically suspended globe
5H25.60 unipolar motor Two magnetized knitting needles mounted as the legs of an "H" suspended by a string rotate when a current flows upward through a rod.
5H25.70 floating magnetic balls Thousands of small magnetic balls floating freely on the surface of water form hills and hollows when excited by a ac magnetic field. Pictures.
5H25.75 Ampere's ants A fun hall display: hide a pushbutton controlled magnetic stirrer under a dish of iron filings.

30. Force on Moving Charges

5H30.10 cathode ray tube Deflect the beam in an open CRT with a magnet.
5H30.10 cathode ray tube A magnet or battery connected to the plates is used to deflect the beam of an open CRT.
5H30.10 e/m for electrons Deflect the beam in an open CRT with a magnet.
5H30.11 measurement of e/m Use the earth's field to deflect the beam in an oscilloscope.
5H30.12 measurement of e/m Deflect the beam of an oscilloscope with large solenoids.
5H30.13 measurement of e/m Deflect the beam of an oscilloscope by current in wires parallel to the axis of the tube.
5H30.14 another tube A Hg tube producing a visible beam is deflected by external magnetic field. Pictures.
5H30.15 bending an electron beam
5H30.15 bending an electron beam
5H30.15 bending of an electron beam An electron beam hitting a fluorescent screen in a tube is bent by a magnet.
5H30.15 deflection of cathode rays A thin beam along a fluorescent screen is bent by a magnet or charged rod.
5H30.15 deflected electron beam A thin electron beam made visible by a fluorescent screen is bent when a magnet is brought near.
5H30.16 induced charges and the Crookes tube A discussion of unwanted deflections of the beam in the Crookes' tube due to induced charge.
5H30.17 CRT and earth's field A CRT is mounted so it can be oriented in any direction and rotated about its axis. Find the position that results in no deflection from the earth's field, turn 90 degrees.
5H30.19 analog computer simulation The motion of a charged particle in a magnetic field is investigated with an analog computer. Circuit diagram for the computer is given.
5H30.20 e/m tube Show the beam of the small e/m tube in Helmholtz coils on tv. A hand held magnet gives a corkscrew.
5H30.20 e/m tube The beam of the small e/m tube in Helmholtz coils is shown on TV A hand held magnet gives a corkscrew.
5H30.21 forces on an electron beam A beam of free electrons is bent in a circle by large Helmholtz coils.
5H30.22 magnetic deflection of cathode rays A beam from a lime-spot cathode in a large bulb is made circular by Helmholtz coils.
5H30.22 "Aurora Borealis" A magnet is brought near a 12 l bulb with a lime-spot cathode.
5H30.24 Classen's e/m Apparatus Drawings Project No. 11: for the advanced undergraduate laboratory.
5H30.25 magnetic mirror
5H30.25 magnetic mirror The effect is better with the Leybold tube.
5H30.25 Van Allen belt Use the tube and magnets to demonstrate trapping of charged particles by the earth's magnetic field.
5H30.25 fine beam tube A fine beam tube between Helmholtz coils.
5H30.26 magnetic mirror effect Bring a bar magnet near the Cenco e/m tube causing charges to spiral into a converging magnetic field.
5H30.29 e/m modificaton Use a half wave rectifier for filament heating.
5H30.29 e/m modification - Welch Use ac instead of dc to heat the filament.
5H30.30 rotating plasma
5H30.30 magnetically suspensed globe A hollow iron globe is suspended from a solenoid with an iron core using a feedback system based on the height of the ball.
5H30.30 rotating plasma A plasma tube powered by an induction coil is placed over an electromagnet.
5H30.40 pinching mercury A thread of mercury in a glass tube is pinched in two by the interaction of the current and the conductor.
5H30.41 bending arc A dc arc bends and may break as a bar magnet is brought close and closer.
5H30.50 electromagnetic pump
5H30.50 electromagnetic pump Mercury is pumped in a tube built so current flows at right angles to the applied magnetic field.
5H30.50 electromagnet pump Current flowing in mercury while in a magnet field causes the mercury to move through a channel. Also shows a paddlewheel version.
5H30.50 electromagnetic pump A closed circuit version of the electromagnetic mercury pump.
5H30.51 magnetic pump Copper sulfate solution flows in a circle when placed between the poles of a magnet with a current from the center to edge.
5H30.52 MHD pump Three versions of MHD pumps: the one for lecture demonstration consists of a loop of Pyrex tubing with NaK as the fluid.
5H30.55 ion motor
5H30.55 ion motor An ion motor for the overhead projector with cork dust in a copper sulfate solution.
5H30.55 rotation of an electrolyte - mag fie Cork dust floating on a solution of zinc chloride in a circular container rotates when current is passed through the solution in the presence of a magnetic field.
5H30.55 ion motor Cork dust shows the motion of copper sulfate an ion motor. Animation.
5H30.56 force on a conducting fluid Salt solution rotates when placed in a circular dish over a magnet with electrodes at the center and edge.

40. Force on Current in Wires

5H40.10 parallel wires Long vertical parallel wires attract or repel depending on the current direction.
5H40.10 parallel wires Long vertical parallel wires attract or repel depending on the current direction.
5H40.10 force between parallel wires Current can be passed parallel or antiparallel in long hanging wires.
5H40.10 parallel wires Two heavy vertical wires 1 cm apart pass 15 - 20 amps in the same or opposite directions.
5H40.10 parallel conductors Vertical parallel wires pass 15 amps.
5H40.11 parallel wires, etc Rectangular loops of solid wire hang on pivots from two stands. Used together, demonstrate parallel wires, or one stand alone can be used for wire in a magnetic field or induced emf.
5H40.12 parallel wires Parallel wires with one being a loop free to turn in pools of mercury.
5H40.13 parallel wires ammeter Modification of the Project Physics exp. 36 gives an accuracy of 3%.
5H40.14 force between parallel wires Radial wires (like clock hands) spring apart when current is passed.
5H40.15 interacting coils Two hanging loops attract or repel depending on current direction.
5H40.15 parallel wires and loops A narrow loop formed by hanging a flexible wire opens when current is passed. Two loops in proximity attract or repel depending on current direction.
5H40.20 pinch effect simulation
5H40.20 pinch effect simulation Same as AJP 32(11),xxiv.
5H40.20 pinch effect simulation Six no. 18 wires are connected loosely between two terminals. Pass 20 amps and the bundle is attracted.
5H40.20 pinch effect Six vertical parallel wires are loosely hung in a circular arrangement.
5H40.20 pinch wires Six wires in parallel attract when current passes through each in the same direction. Then sets of three wires each have current flowing in opposite directions.
5H40.21 pinch effect A high voltage capacitor is discharged through a cylinder of aluminum foil strips.
5H40.23 filament and magnet with AC/DC
5H40.23 vibrating lamp filament A tube lamp with a straight filament on AC will vibrate when placed between the poles of a magnet.
5H40.23 vibrating lamp filament A magnet is brought near carbon filament lamps, one powered by AC, the other by DC. The images are projected.
5H40.23 AC/DC magnetic contrast A magnet is brought near a carbon lamp filament powered by DC, then AC.
5H40.24 AC driven sonometer A sonometer tuned to resonate at a harmonic of 60 Hz is driven by passing AC through the wire while between the poles of a magnet.
5H40.25 dancing spiral
5H40.25 dancing spiral Current is passed through a limp copper spring dangling in a pool of mercury causing it to dance.
5H40.25 dancing spring A helix of fine wire hanging vertically into a pool of mercury contracts and breaks contact repeatedly.
5H40.30 jumping wire A wire is placed in a horseshoe magnet and connected to a battery. The wire jumps out of the magnet.
5H40.30 magnetic force on a wire A wire is placed in a horseshoe magnet and connected to a battery.
5H40.31 jumping wire A large heavy wire clip rests in pools of mercury between the poles of a strong magnet.
5H40.32 aluminum bar in a magnet An aluminum bar in a magnet has its ends in mercury. Short the mercury pools to a storage battery and the aluminum bar hits the ceiling.
5H40.33 electomagnetic circuit breaker A wire hangs into a pool of mercury and between the poles of a "U" shaped magnet. As current is passed through the wire, it deflects out of the mercury and breaks the circuit.
5H40.34 lead foil in magnet A strip of lead foil is supported vertically between the poles of a "U" magnet so it is free to move a few cm when a few dry cells are connected through a reversing switch.
5H40.35 jumping wire coil
5H40.35 jumping wire A coil of wire wound around one pole of a horseshoe magnet jumps off when energized.
5H40.35 jumping wire coil Run twenty amps through a wire in a horseshoe magnet.
5H40.36 long wire in field
5H40.36 long wire in field
5H40.37 take apart speaker Add abstract in Handbook.FM
5H40.40 current balance
5H40.40 current balance An open rectangle of aluminum wire is balanced between the poles of a "U" magnet until current is passed through the part perpendicular to the field.
5H40.42 triangle on a scale in a magnet A triangular loop of wire is hung from a spring scale in the mouth of a electromagnet and the current in the loop is varied.
5H40.43 improved current balance Improvements on the Sargent-Welch current balance increasing the range to 20 A.
5H40.43 modified current balance Add molten Wood's metal contacts to the Sargent Welch current balance.
5H40.43 current balance The Welch current balance.
5H40.44 current balance Design of a current balance with a rectangular coil on knife edges and stationary windings with parallel conductors.
5H40.46 Maxwell's rule Demonstrates an electric circuit that can change shape to include the maximum possible magnetic flux. A heavy wire connects two metal boats floating in mercury troughs with electrodes at one end.
5H40.48 CERN floating wire pulley Shows a pulley for the "floating wire" technique of simulating a beam of particles in magnetic fields. The method can be adapted to measure the radius of curvature of a wire in a magnetic field.
5H40.50 Barlow's wheel
5H40.50 Barlow wheel A copper disk with current flowing from the center to a pool of mercury at the edge rotates when placed between the poles of a horseshoe magnet.
5H40.50 Barlow's wheel A potential is applied from the axle of a wheel to a pool of mercury at the rim while the wheel is between the poles of a magnet.
5H40.50 Barlow's wheel Current passes from the bearings of a copper wheel mounted vertically to a pool of mercury at the base. A "U" shaped magnet is mounted so the current is perpendicular to the magnetic field.
5H40.50 Barlow's wheel A picture of the standard vertical disc in a pool of mercury.
5H40.50 Barlow's wheel Current flows radially in a disc mounted between the poles of a magnet.
5H40.52 Barlow's wheel The copper disk in Barlow's wheel is replaced by a cylindrical Alnico magnet with the field parallel to its axis.
5H40.53 homopolar motor Variation of Barlow's wheel. An Alnico disk, magnetized in the direction of the axis, rotates around the axis when a current is made to flow from the axis to the rim.
5H40.55 conducting spiral A conducting spiral is constructed as a simplified unipolar machine.
5H40.60 electromagnetic swing Switch the current direction in a wire loop swing mounted above one pole of a vertical bar magnet to build up a pendulum motion.
5H40.61 magnetic grapevine A very flexible wire suspended alongside a vertical bar magnet will wrap itself around the magnet when there is a current in the wire.
5H40.62 electromagnetic conical pendulum A vertical wire is suspended loosely from above a vertical solenoid into a circular trough of mercury. As current is passed through the wire, it rotates in the trough.
5H40.70 Ampere's motor
5H40.70 Ampere's frame A coil on a reversing switch is placed between the poles of strong magnets.
5H40.70 Ampere's frame A magnet is brought near and rotates a large current carrying loop.
5H40.71 Ampere's motor A copper rod rolls along two electrified rails over ring magnets sandwiched between steel plates.
5H40.71 Ampere's motor A wheel on electrified rails over a large vertical field produced by electromagnets rolls back and forth depending on the current direction. Picture.
5H40.71 Ampere's motor As the current is reversed in a rod rolling horizontally on a track between the poles of a strong magnet, the direction of motion reverses.

50. Torques on Coils

5H50.10 model galvanometer
5H50.10 model galvanometer A crude galvanometer with a large coil and magnet demonstrates the essentials.
5H50.10 galvanometer with permanent magnet An open galvanometer with a permanent magnet.
5H50.10 elements of a galvanometer A large working model of a galvanometer.
5H50.10 d'Arsonval galvanometer A large model d'Arsonval galvanometer is constructed from a coil and a large "U" shaped magnet.
5H50.10 D'Arsonval meter A large open galvanometer.
5H50.20 force on a current loop
5H50.20 force on a current loop
5H50.20 Joseph Henry A rectangular loop on wire aligns perpendicular to a magnetic field. Reference: TPT 3(1),13.
5H50.25 short and long coils in field
5H50.25 short and long coils in field
5H50.30 interacting coils
5H50.30 interaction of flat coils A small free turning coil is mounted in a larger coil.
5H50.30 interacting coils Two horizontal coaxial coils, the inner stationary and the outer larger coil suspended freely, interact when currents are passed through in like or opposite directions.
5H50.30 interacting rotating coils Add abstract in Handbook.FM
5H50.31 coil in coils A solenoid attached to a battery is mounted in a large open Helmholtz coils assembly. ALSO - three other demos with the Helmholtz coils. Pictures.
5H50.32 interacting solenoids Two heavy copper horizontal solenoids pivot in mercury cups about a vertical axis.
5H50.35 dipole loop around long wire
5H50.40 solenoid in a magnetic field Suspend a solenoid and show the effects of a bar magnet on it.
5H50.41 floating coil A vertical coil energized by a flashlight cell floats in a large pan. Use a bar magnet to move the coil.
5H50.45 spinning coil over magnet
5H50.45 spinning coil over magnet


10. Self Inductance

5J10.10 inductor assortment
5J10.10 inductor assortment Sample inductors are shown.
5J10.20 back EMF - light bulb
5J10.20 back EMF A 20 Henry inductor energized by a 12 V battery lights a 120 V 7 1/2 W lamp when the circuit is opened.
5J10.20 back EMF When current is cut off in the primary, a meter in parallel shows an induction current in the primary.
5J10.20 self inductance Open the switch of a large electromagnet with a lamp in parallel.
5J10.20 inductance spark Disconnect a 6 V battery from a 2000 turn coil to get a spark, enhance with an iron core.
5J10.21 back EMF A 4.5 V battery lights a neon bulb when the current to an inductor is disrupted.
5J10.22 neon back EMF The coils of a electromagnet are connected in parallel with a neon bulb.
5J10.23 neon self induction A neon lamp across an inductor will glow on one side during charging and will flash on the other when the current is interrupted.
5J10.25 inductance and the wheatstone bridge The galvanometer in a Wheatstone bridge is connected after an inductor has reach steady state or at the same time the current is started in the inductor.
5J10.26 simulating ideal self-induction A nulling circuit compensates for the steady state current in a coil.
5J10.30 back EMF - spark
5J10.30 back emf spark A one inch spark is produced when the switch of a large electromagnet is opened.
5J10.32 electromagnetic inertia A spark will jump across an almost closed loop of wire rather than go around when attached to a Leyden jar.

20. LR Circuits

5J20.10 RL time constant on scope Show the RL time constant on a scope.
5J20.10 LR time constant on scope The current and voltage of an slow time constant LR circuit are displayed on a dual trace storage oscilloscope.
5J20.10 L/R time constant A plug in circuit board with a make before break switch for showing slow RL time constants on the oscilloscope.
5J20.10 RL time constant The RL time constant is shown on a scope.
5J20.11 time constant of an inductive cir. Compare the time constant of an inductor using different cores on an oscilloscope.
5J20.20 lamps in series or parallel with ind. Hook light bulbs in series with a large electromagnet.
5J20.20 current in an inductive circuit Light bulbs across and in series with a large electromagnet show the current in an inductive circuit.
5J20.20 lamps in series and parallel on EM Two lamps are used to indicate voltage across and current through a large electromagnet.
5J20.20 series lamps on an EM Light bulbs are hooked up in series with a large electromagnet.
5J20.20 lamps in parallel with solenoid Apply 110 V to a large solenoid with incandescent and neon lamps in parallel. The neon lamp flashes on the opposite side on discharge.
5J20.21 lights in series and parallel A circuit with a 5 H inductor has neon lamps in series and in parallel.
5J20.25 inductor characteristics A bulb in parallel with a coil does not burn when powered by dc, but does when coupled to a high frequency source.
5J20.30 LR time constant Substitute a inductor and resistor of the same R in a circuit that lights a neon bulb.

30. RLC Circuits - DC

5J30.10 RLC ringing
5J30.10 RLC ringing The voltages across the L and C of a slow RLC circuit are displayed on a dual trace storage oscilloscope while the circuit is energized and de energized.
5J30.10 characteristic times in a parallel Slow parallel RLC ringing on an oscilloscope.
5J30.10 ringing circuit Ringing from an RLC circuit is shown on an oscilloscope.
5J30.10 characteristic times in a series RLC Slow series RLC ringing on an oscilloscope.
5J30.10 RLC ringing A circuit for showing LC ringing on a oscilloscope.
5J30.11 damped LRC oscillation Discharge a capacitor through a series LRC circuit. Vary the capacitance and resistance.
5J30.15 RLC ringing A motor driven commutator switches a circuit from charging to discharging so RLC ringing decay can be observed on an oscilloscope. Picture, Diagram, Construction details in appendix, p.1334.
5J30.20 RLC ringing A DC circuit with RC charging and RLC discharging.
5J30.21 RLC ringing A circuit to charge a capacitor either with or without an inductance in series.
5J30.30 singing arc A ordinary carbon arc is shunted by a series LC circuit.


10. Induced Currents and Forces

5K10.10 sliding rail
5K10.10 sliding rail Slide a brass bar riding on two brass rails out of the mouth of a horseshoe magnet and display the current on a galvanometer.
5K10.10 sliding rail inductor Slide a bar on rails attached to a galvanometer through the mouth of a horseshoe magnet.
5K10.11 mu metal sheild The sliding rail with a mu-metal shield gives the same result.
5K10.12 mu metal shield and insulator The sliding rail with an insulated mu-metal shield still gives the same result.
5K10.13 motional EMF Directions on making an apparatus for demonstrating motional EMF. Reference: Am. Phys. Teacher, 3,57,1935.
5K10.15 wire, magnet, and galvanometer
5K10.15 moving wire with magnet A straight wire connected to a galvanometer is moved rapidly through the poles of a strong magnet.
5K10.15 Wire and magnet Move a wire connected to a galvanometer in and out of a horseshoe magnet.
5K10.16 tape head model
5K10.17 swinging bar in magnet A bar connected to a galvanometer is swung in and out of a permanent magnet. ALSO - two other demonstrations.
5K10.18 coil pendulum in magnet A 1 second pendulum with a coil for a bob swings with small amplitude within a uniform magnetic field. All sorts of variations demonstrating forced, free, and damped oscillations are mentioned.
5K10.19 measuring magnetic induction A rectangular coil in a magnetron magnet is rotated on one side and the other is suspended from a balance. Change the current in the coil and measure the force with the balance.
5K10.20 induction coil with magnet, galv. A magnet is moved in and out of a coil of wire attached to a galvanometer.
5K10.20 induction coil with magnet, galv. A magnet is moved in and out of a coil of wire attached to a galvanometer.
5K10.20 big coil Make the coil large enough for the instructor to walk, run, etc. through.
5K10.20 galvanometer, coil and magnet Move a magnet through a coil connected to a galvanometer.
5K10.20 direction of induced currents Use each end of a magnet with a coil and galvanometer.
5K10.20 induction coil and magnet Move a bar magnet in and out of a coil connected to a galvanometer. Turn the coil with a fixed magnet.
5K10.20 induction coil, magnet, galvanometer A many turn coil attached to a projection galvanometer is flipped over or a magnet is thrust through.
5K10.21 10/20/40 coils with magnet
5K10.21 10/20/40 coils with magnet Coils of 10, 20, and 40 turns are attached to a galvanometer.
5K10.22 string and copper induction coils A magnet is passed in and out of a copper coil hooked to a millivoltmeter and string loop hooked to an electrometer.
5K10.23 mutiple induction coils Wind coils 1:2:4:4:4 with the 2nd and 4th in the opposite sense, all in series. Use with a single pole, then use two poles of a horseshoe magnet in two adjacent coils.
5K10.24 number of turns and induced EMF Combine coils of 5 cm diameter with 1,2,5,10,15 turns in various ways to show induced EMF proportional to number of turns.
5K10.25 coil and lamp, magnet
5K10.25 coil and lamp, magnet
5K10.25 inductive coil with lamp Swing a coil attached to a lamp through the gap of a horseshoe magnet.
5K10.26 induction effects of hitting the bar Put a 600 turn coil connected to a galvanometer around a soft iron bar and hit the bar while oriented parallel and perpendicular to the earth's field.
5K10.30 induction with coils and battery Attach one coil to a galvanometer, another to a battery and tap switch. Use a core to increase coupling.
5K10.30 induction with coils and battery Two coils face each other, one attached to a galvanometer, the other to a battery and tap switch. Coupling can be increased with various cores.
5K10.30 galvanometer, coils and battery Two coils are in proximity, one attached to a galvanometer, the other to a switch and battery.
5K10.30 induction coils with battery Change the position of the secondary as the current is interrupted in the primary.
5K10.30 two coils Changing the current in one coil causes a current in the other.
5K10.31 induction coils with battery Two coils are wound on an iron ring, one connected to a galvanometer, the other to a battery and switch.
5K10.32 induction coils and battery Two coils, one connected to a galvanometer, the other to a battery through a rheostat to allow continuous variation of current.
5K10.33 induction coils with battery The voltage to a long three layered solenoid is interrupted with various layers active and various sensor loops inside.
5K10.36 discovering induction Repeat the original Faraday experiment and no one realizes the galvanometer twitch is meaningful.
5K10.37 ramp induction coils A galvanometer detects a steady current from one Helmholtz coil as a second coil is excited with a voltage ramp.
5K10.38 changing the air gap Change the air gap between two coils and show the induced voltage.
5K10.39 current from changing air gap Change the size of the air gap in an electromagnet and observe a transient change in the current energizing the coil.
5K10.40 induction coils with core
5K10.40 iron core in mutual inductance The effect of an iron core is demonstrated as a battery is connected to the primary.
5K10.41 insert core While one coil has a continuous current, insert and remove cores of iron, copper, and brass.
5K10.42 two coils on a toroid Two coils wound on opposite sides of a toroidal core show inductive coupling when current is switched in one coil.
5K10.45 large mutual inductance Change the current steadily in a large transformer and watch the voltage in the secondary.
5K10.48 current coupled pendula
5K10.48 current-coupled pendula Interconnected coils are hung as pendula in the gaps of two horseshoe magnets. Start one swinging and the other swings.
5K10.50 time integral of induced EMF The induced current from a coil is displayed on a storage oscilloscope while the current is changed at various rates in a second coil.
5K10.52 induction on the air track A loop of wire on an air cart passes through a magnet. Show on a scope.
5K10.55 HO car in a magnetic tunnel The induced EMF is observed on an oscilloscope as a brass wheeled train car passes along a track through a large magnet.
5K10.60 earth inductor
5K10.60 earth inductor the deflection of a ballistic galvanometer from a flip coil is compared to a standard flux.
5K10.60 Earth coil Flip the standard Earth coil attached to a galvanometer.
5K10.61 earth inductor Several variations. A large (1.5 m x 6 m) single wire loop, collapse a flexible loop on many turns, a long flexible wire swung like a jump rope are attached to a galvanometer with the damping turn removed. ALSO the commercial loop to a ballistic galvanometer.
5K10.62 rotating coil magnetometer Orient a motor driven coil in various ways in the earth's field while the output is displayed on an oscilloscope.
5K10.62 earth inductor integrating amp Replace the ballistic galvanometer with an integrating amp (circuit given).
5K10.62 earth inductor with VFC A voltage-to-frequency converter replaces the ballistic galvanometer in the earth inductor demonstration.
5K10.62 earth inductor on oscilloscope Subsititute an oscilloscope for the galvanometer and look at the induced voltage versus time.
5K10.62 earth inductor integrator Replace the galvanometer with a integrator and voltmeter.
5K10.63 rotating coil magnetometer Display the signal from a motor driven coil on an oscilloscope.
5K10.63 earth inductor compass A motor driven coil of several hundred turns gives a different galvanometer deflection depending on the orientation.
5K10.65 jumping rope
5K10.65 jumping rope
5K10.70 What does a voltmeter measure?
5K10.70 What does a voltmeter measure? Same as AJP 50(12),1089.
5K10.70 what do voltmeters measure? Two identical voltmeters connected at the same points in a circuit around a long solenoid give different readings.
5K10.71 paradox Feynman - "When you figure it out, you will have discovered an important principle of electromagnetism".
5K10.71 what does a voltmeter measure-letter Add a third voltmeter that can be moved for continuously varying readings.
5K10.71 Faraday's law teaser Measure the voltage between two points at the end of an electromagnet through different paths.
5K10.71 Faraday's law teaser - addendum Clears up ambiguities in AJP 37(2),221.
5K10.78 induced current liquid crystal Liquid crystals placed over laminated copper conductors show heating of various configurations.
5K10.80 Faraday's homopolar generator Turn a large aluminum wheel by hand with the edge of the wheel and a pickoff brush between the poles of a magnet. Show the induced current on a galvanometer.
5K10.80 homopolar generator A homopolar generator shows the relation between electric and magnetic fields. Not the most obvious demonstration.
5K10.81 radial homopolar generator A variation on the axial field homopolar motor (Barlow's wheel).
5K10.85 Rogowski coil A direct demonstration of Ampere's circuital law using a flexible toroidal coil.
5K10.85 magnetic wheel Induced current from a unipolar machine using a magnetic wheel.
5K10.85 Rogowski coil A flexible coil hooked to a ballistic galvanometer is used to give a direct measurement of the magnetic potential between two points.
5K10.85 Ampere's law Use the Rogowski coil to examine the magnetic field produced by current in a single wire, or two wires of parallel and opposing current. Picture, theory.
5K10.90 electromagnetic can breaker A large pulse of induced current in a soda can blows it apart.
5K10.99 rocking plates Demonstrates some difficult concepts of flux linkages using sheets of metal instead of wires.

20. Eddy Currents

5K20.10 Eddy currents in pendulum A copper sheet and comb, ring and broken ring are swung through a large electromagnet.
5K20.10 pendulum in big electromagnet Pendula of solid and comb-like copper plates, solid and slit copper rings are swung through a large electromagnet.
5K20.10 Eddy current pendulum Apparatus Drawings Project No. 29: Large electromagnet accessories, one of four. Plans for a large eddy current pendulum to go on the large electromagnet from No. 13.
5K20.10 Eddy currents in pendulum A copper sheet and comb, ring and broken ring are swung through a large electromagnet.
5K20.10 Eddy current pendulum Copper, wood, etc. bobs are swung in a large permanent magnet.
5K20.11 magnetic brake A heavy copper disk swings as a pendulum between the poles of an electromagnet.
5K20.11 Eddy current pendulum A pendulum with a copper plate bob is swung through a big electromagnet.
5K20.15 Eddy damped pendulum
5K20.15 eddy damped pendulum A magnet pendulum bob is swung over copper, aluminum, and stainless plate.
5K20.15 eddy damped pendulum A bar magnet suspended as a pendulum is damped as it swings over a copper plate.
5K20.20 falling aluminum sheet
5K20.20 falling aluminum sheet An aluminum sheet is dropped through the poles of a large horseshoe magnet.
5K20.20 falling aluminum sheet A strip of aluminum sheet is allowed to fall between the poles of a large Alnico magnet.
5K20.22 Eddy current brake Fasten a large aluminum disk to a 1/4 hp motor and then bring a magnetron magnet to the edge of the disk to slow the motor down.
5K20.25 magnets in Eddy tubes Drop a magnet and a dummy in glass and aluminum tubes, then switch. The magnet in Al falls slowly.
5K20.25 magnets and eddy tubes
5K20.25 Eddy current tubes Drop a magnet and a dummy in glass and aluminum tubes, then switch.
5K20.26 Faraday repulsion coil
5K20.26 forces due to induced current Pull a light bifilar suspended aluminum ring with a magnet.
5K20.26 Faraday repulsion coil Thrust the pole of a magnet in and out of a copper ring of a bifilar suspension.
5K20.30 jumping ring A solid aluminum ring on the vertical transformer jumps while a split ring does not.
5K20.30 jumping ring Aluminum rings, one slit, the other solid, are placed around the core of a coil and the the coil is energized.
5K20.30 jumping ring An aluminum ring jumps off the iron core of a vertical inductor.
5K20.30 jumping ring Solid and split aluminum rings on the vertical transformer.
5K20.30 Thompson's flying ring A copper ring levitates, an aluminum ring flies off, a slit ring does nothing, and a cooled ring flies higher.
5K20.31 jumping ring analysis An analysis of the role of phase differences in the levitating ring demonstration.
5K20.31 jumping ring analysis An analysis of the role of phase differences in the levitating ring demonstration.
5K20.31 jumping ring analysis Be careful how you analyze the jumping ring. References.
5K20.35 frying egg A copper sheet fitting over the core of a large solenoid gets hot enough to fry an egg.
5K20.36 boil water on the vertical transform Boil water in a ring shaped trough on the vertical transformer.
5K20.40 Eddy current levitator
5K20.40 Eddy current levitator
5K20.40 Eddy current levitation A strong ceramic magnet is levitated over a spinning aluminum disc.
5K20.41 electromagnetic levitator Plans for an electromagnetic levitator that lifts a 18" dia. 1/16" thick aluminum pan. Weighs 100 lbs, requires only 400 W at 110 V.
5K20.41 large levitator Directions for building a large levitator. Diagrams, Construction details in appendix, p. 1332.
5K20.42 Arago's disk
5K20.42 Arago's disk Support the horseshoe magnet by a bight with stranded string and "wind up" the string to get a high spin rate.
5K20.42 Arago's disk A magnet suspended above a rotating horizontal copper disk will rotate.
5K20.42 rotating magnet A magnet needle over a rotating copper disk.
5K20.42 Arago's disk A bar magnet suspended above a spinning aluminum disc will start to rotate.
5K20.43 rotating vertical disc A magnet hung by a quadrafilar rolling suspension near a spinning aluminum disk shows both repulsive and retarding forces.
5K20.50 rotating ball
5K20.50 rotating ball A hollow aluminum ball rotates in a watch glass atop a shaded pole transformer.
5K20.50 spinning ball on a dish A half disc of sheet aluminum placed on an ac excited coil produces a rotating magnetic field the at causes a ball to spin.
5K20.51 magnetic stirrer demonstrations Several eddy current demos including a paradox: place a steel ball on a stirrer and start it up, the ball rolls in one direction, but backwards when placed in while the stirrer is on.
5K20.52 Eddy current motor A metal 35 mm film canister spins when mounted to one side of the pole of an electromagnet.
5K20.55 rotating aluminum disc An aluminum disc rotates when held asymmetrically over a vertical solenoid powered by line ac unless shielded by an aluminum plate.
5K20.56 spinning aluminum discs Two overlapping rotating aluminum discs in parallel planes on the same rigid support rotate in different directions when inserted into a magnetic field. Needs a Diagram.
5K20.57 rotating aluminum disc A thin aluminum disc hung vertically between the poles of a vertically mounted horseshoe magnet rotates when the magnet is rotated.
5K20.58 one-piece Faraday generator Instead of a conducting disk rotating in an axial magnetic field, the disk is replaced by a cylindrical permanent magnet that supplies its own magnetic field.
5K20.59 magnetic curl meter Faraday's "electromagnetic rotation apparatus" shows a magnet in a conducting fluid rotating continuously when suspended in a region of distributed current density. This device measures the torque on such a magnet.
5K20.60 Eddy currents in Barlow's wheel Attach the Barlow's wheel to a galvanometer and turn by hand.
5K20.62 money sorter Silver and ersatz quarters are dropped through a large magnet.
5K20.63 rotating cores in magnet A copper loop, solid iron cylinder, and laminated iron cylinder are each rotated while suspended in a magnetic field.
5K20.65 electromagnetic can breaker

30. Transformers

5K30.10 wind a transformer
5K30.13 salt water string
5K30.14 single turn transformer Probes of an oscilloscope are slid along the ring of a single turn secondary.
5K30.20 dissectible transformer/light bulb
5K30.20 dissectible transformer Various cores are interchangeable with the Leybold transformer.
5K30.20 transformers Many variations with the Leybold transformer.
5K30.21 toy transformer Place a 110 V lamp in parallel with the input and a 6 V lamp on the output of a step down transformer. Then place a auto taillight lamp in series with the input and a 10 amp fuse wire across the output and increase the voltage with an autotransformer until the fuse melts.
5K30.22 telephone and radio transformers Using commercial transformers in demonstrations.
5K30.24 magnet losses in transformers Additional cores are placed in the Leybold transformer to demonstrate the magnetic potential drop.
5K30.25 transformers High voltage, low voltage and demonstration transformers are shown.
5K30.30 vertical transformer
5K30.30 vertical transformer Secondary loops attached to light bulbs are placed over the core of a vertical transformer.
5K30.30 vertical transformer Directions for making a vertical transformer using 110 V AC in the primary. Includes directions for step up and step down secondaries.
5K30.30 Thompson vertical transformer A vertical transformer is shown with a lot of accessories.
5K30.30 vertical primary and secondary coils The vertical transformer is used with two coils, one with many turns powers a 110 V lamp, and the other with fewer turns powers a flashlight lamp.
5K30.34 autotransformer A variation of the vertical transformer with 400 turns tapped every 50 turns and connected to 110 V AC at 200 turns. Explore with a light bulb. See L-99.
5K30.35 light underwater
5K30.35 light underwater The secondary coil and light bulb are placed in a beaker of water and held over the core of a vertical transformer.
5K30.35 light under water A waxed coil and light bulb are placed in a beaker of water over a vertical primary.
5K30.40 weld a nail
5K30.40 weld a nail Two nails attached to the secondary of a large low voltage transformer are welded together upon contact.
5K30.40 large current transformer Nails connected to the secondary of a large current transformer are welded together.
5K30.40 dissectible transformer - welding Two "L" shaped laminated iron cores with interchangeable coils are used to step down 110 V AC to melt an iron wire.
5K30.43 simple spotwelder Modify a heavy duty soldering iron to function as a small spotwelder.
5K30.50 Jacob's ladder see 5D40.10
5K30.51 induced EMF An oscilloscope is connected to a wire in a gap of a transformer.
5K30.52 exploratory coil Explore an alternating magnetic field with an exploratory coil of many turns of No. 30 wire connected to a 6 V lamp.
5K30.53 mutual inductance on scope The relationship between the current in one coil and the voltage in another is shown as a Lissajous figure on an oscilloscope. Diagram.
5K30.54 magnetic shunt An "E" core has two windings: 110V primary on one outer, and secondary with a lamp on the middle. Bridge a yoke over the windings and the lamp lights but when put over all three it doesn't.
5K30.60 reaction of a secondary on primary
5K30.60 primary current change with sec.load A light bulb in series with the primary brightens as the load on the secondary increases.
5K30.60 reaction of secondary on primary Connect a 100 W lamp in series with the primary and increase the load on the secondary to light the lamp.
5K30.61 reaction of secondary on primary Vary the load on the secondary and the coupling between the primary while observing the current in the primary.
5K30.81 shocker A vibrator switches the current in a primary and the victim holds onto the leads of the secondary while the coupling is increased.
5K30.84 phony health belt A weird antique health belt.
5K30.90 resonant Leyden jar detector One Leyden jar with a loop of wire is driven with a induction coil, another similar arrangement is used as a detector.
5K30.90 Leyden jar and loop When a spark jumps from a loop of wire to a Leyden jar, a small spark will jump in a similar device close by.

40. Motors and Generators

5K40.10 DC motor
5K40.10 DC motor A coil is mounted between two magnetron magnets.
5K40.10 DC motor A large open coil is mounted between the poles of magnetron magnets to make a DC motor.
5K40.10 DC motor A circular loop of heavy wire between two solenoids with iron cores.
5K40.10 DC motor A coil in a "U" shaped magnet with a simple commutator.
5K40.10 DC motor A large model DC motor.
5K40.12 DC motor and lamp A DC motor has a light bulb in series with the armature to indicate current flow as the motor starts, comes up to speed, and is under load.
5K40.13 DC series and parallel motors A DC motor on a board allowing armature and field to be connected in series or parallel.
5K40.15 Faraday motor
5K40.15 Faraday motor Apparatus Drawings Project No.33: A rod magnet sticks up through a pool on mercury and a parallel conducting copper wire is free to move in a circle around the magnet.
5K40.15 Faraday motor A model of the first electric motor developed by Faraday.
5K40.15 Faraday disc Spin a copper disc between the poles of a horseshoe magnet with brushes at the center and edge of the disc connected to a galvanometer.
5K40.18 simple motor A two coil, two magnet assembly illustrates simple generator principles.
5K40.19 simple speed control for DC motor A circuit to change speed and direction of a small DC motor.
5K40.20 DC & AC generators on galvanometer
5K40.20 DC & AC generators on galvanometer A coil mounted between two magnetron magnets is equipped with both commutator and slip rings.
5K40.21 motor waveform The armature of a generator is rotated 10 degrees at a time to a ballistic galvanometer and the result of 36 observations are plotted.
5K40.25 DC & AC generators on scope
5K40.25 DC & AC generators on scope The waveforms from the DC/AC generator are displayed on an oscilloscope.
5K40.26 ac and dc dynamo demonstration Abstract from the 1981 apparatus competition.
5K40.27 model generator A generator built with small motor spun rotor in a large open solenoid shows operation of an ac generator.
5K40.28 light the bulb with a coil A coil connected to a light bulb is mounted on a disk rotating between the poles of an electromagnet. Picture.
5K40.29 generator on the overhead A hand crank generator designed for use on the overhead projector.
5K40.40 motor/generator A large AC/DC motor/generator has both slip and split rings.
5K40.40 motor/generator
5K40.40 motor generator An armature with both slip rings and a commutator allows operation of a coil between two magnets as either a AC or DC motor or generator.
5K40.40 motor/generator A coil mounted between the poles of an electromagnet is rotated by hand as a generator or powered by a battery as a motor.
5K40.40 AC and DC generators Directions for making a large demonstration motor/generator. Picture.
5K40.40 ac/dc generator A large AC/DC generator with slip and split rings.
5K40.45 coupled motor/generator
5K40.45 coupled motor/generators Two small permanent magnet dc motors are coupled so when one is driven mechanically, the other will spin. Picture.
5K40.50 simple induction motor Bring a coffee can on an axle near two coils mounted at 90 degrees carrying ac with a capacitor in one line.
5K40.53 induction motor model Suspend a closed copper loop by a thread in the gap of a rotating magnetron magnet and it will remain aligned with the rotating field.
5K40.55 synchronous motor Run an AC dynamo as a synchronous motor by supplying AC to the armature coils.
5K40.56 synchronous and induction motors Three pairs of coils in a circle produce a rotating magnetic field for use with a permanent magnet or aluminum rotor. Picture, Construction details in appendix, p. 1329.
5K40.60 three phase Directions for winding three coils of a three phase rotator.
5K40.60 three phase Directions for making a three phase winding and things to spin in it.
5K40.61 three phase Remove the rotor from a three phase induction motor and place a steel ball inside.
5K40.64 modified Rowland ring An aluminum ring spins in the center of a three phase horizontal toroid. Picture.
5K40.65 two phase rotator How to make a two phase rotator get two phase from either three phase or two phase. Diagram.
5K40.70 counter EMF in a motor A lamp in series with a motor does not glow unless a load is placed on the motor slowing it down.
5K40.71 counter EMF in a motor Suddenly switch the armature of a shunt wound DC motor to a voltmeter while it is running.
5K40.72 back EMF in a motor The circuit that shows the effect of back EMF on current drawn by a motor under various load conditions and after it is turned off. Diagram.
5K40.73 speed of AC motors under load Slip speed and phase shift are shown stroboscopically as the load is increased on induction and synchronous motors.
5K40.75 motor debunking A copper conductor in an iron tube in a magnetic field shows forces in most motors are not caused by magnetic fields set up in the conductors.
5K40.80 hand crank generator Use a hand cranked generator to light an ordinary light bulb.
5K40.80 hand crank generator Light a bulb with a hand crank generator.
5K40.80 hand crank generator A hand crank generator made with a 120 V DC generator is used with light bulbs.
5K40.80 hand crank generator A hand cranked generator is used to light an ordinary light bulb.
5K40.80 hand cranked generator Students light a bulb with a hand crank generator.
5K40.80 telephone generator An AC generator from an early telephone lights a 110 v lamp. Also- a single loop model and another generator.
5K40.80 hand cranked generator A hand cranked generator slows down in five seconds from internal friction or in one second while lighting a lamp.
5K40.82 AC and DC generator A small open hand crank generator.
5K40.83 bicycle generator
5K40.83 bicycle generator A 2KW generator mounted on a bicycle is used with big lamps.
5K40.85 generator slowed by load
5K40.85 generator driven by falling weight A weight on a string wrapped around the shaft of a generator falls more slowly when there is an electrical load on the generator.
5K40.99 MHD power generator Discharge a toy rocket motor between the poles of a magnet and attach copper electrodes placed in the gas jet to a voltmeter.


10. Impedence

5L10.10 inductive choke
5L10.10 inductive choke Move a core in and out of a coil in series with a light bulb.
5L10.10 variable inductance An inductor with an movable iron core is connected in series with a light bulb.
5L10.10 inductive reactance Pull a core in and out of a solenoid in series with a 200W lamp, then a 10 W lamp. Try with DC.
5L10.10 inductor with lamp on AC Place a large coil in series with a light bulb, then insert an iron core in the coil and the light bulb dims.
5L10.20 capacitive impedance
5L10.20 capacitive impedence A variable capacitor is connected in series with a light bulb.
5L10.30 capacitive reactance
5L10.30 capacitive reactance A circuit to vary R through the value of the capacitive reactance, among other things.
5L10.35 capacitive reactance Measure the voltage and phase across each element in a circuit with a 25W lamp in series with a capacitor.
5L10.40 skin effect Conductors of different dimensions are connected to lamp indicators in a high frequency circuit.
5L10.41 skin effect Stack metal plates between the primary and secondary of a transformer, a bundle of wire is opened up to gain access to any wire for a current measurement.
5L10.50 phasemeter Some phasemeter circuits are given suitable for showing current-voltage relationships for reactive elements.
5L10.51 I-V curves on a scope A circuit to generate I-V curves of various electrical components. Diagram, Appendix: p. 1337.
5L10.55 octopus A simple circuit used by technicians to probe the relationship of current and voltage in a circuit.
5L10.55 impedence bridge Complex impedances are plugged into a Wheatstone bridge board.

20. LCR Circuits - AC

5L20.10 RLC - phase differences
5L20.10 LCR - phase differences Applied voltage, R, L, and C are displayed on a four channel scope while L is changed and the circuit passes through resonance.
5L20.10 parallel resonance Transformers permit viewing voltages in all elements of a parallel RLC circuit.
5L20.10 phase shift in an LRC circuit The voltages across elements of a RLC circuit are shown as the inductor is varied through resonance.
5L20.10 LCR series circuit Isolation transformers permit viewing applied, R, L, and C simultaneously on an oscilloscope as the inductor is varied through resonance.
5L20.11 series RLC phase shift on scope Simultaneous display of four traces of the RLC circuit on a single channel scope using a multiplexer. Circuit diagrams are given.
5L20.11 RLC phase relationships A circuit allows phase relationships between R and L or C of the Cenco 80375 choke coil and resonance apparatus to be displayed on an oscilloscope.
5L20.12 LCR waveforms display The Leybold double wire loop oscillograph is modified to project laser beams showing the current and voltage relationships of a LRC (circuit given) circuit.
5L20.13 LCR phase relationships Show the input and output of an RLC circuit on a dual trace oscilloscope.
5L20.14 phase shift in fluorescent circuit Among other things, demonstrate the phase shift in a fluorescent lamp circuit.
5L20.14 LC op amp interface OP amps placed across the inductor and capacitor have high impedance and do not perturb the system.
5L20.15 LCR - phase differences A neon lamp detector shining on a disk rotated by a synchronous motor shows phase differences in a series RLC circuit driven by 110 V AC.
5L20.16 LCR vectors on CRO Pulses are generated from an RLC circuit to modulate the Z axis of a CRO. The dots shift as the applied frequency is changed.
5L20.17 seconds period LCR Directions for building an underdamped LCR circuit with a period from .5 to 5 seconds. Forced oscillation with a electromechanical generator.
5L20.18 driven LRC circuit
5L20.18 driven LRC circuit The voltage and current across the capacitor, inductor, resistor, and supply are shown in succession on an oscilloscope.
5L20.20 RLC - resonance
5L20.20 RLC - resonance A large lamp lights in a 60 Hz 120 V RLC circuit when the L is changed and resonance is achieved.
5L20.20 series LRC circuit The light bulb in a RLC circuit glows when the inductor core is moved through resonance.
5L20.20 series RLC resonance A 110 VAC lamp, capacitor, and variable inductor form a series circuit.
5L20.20 series RLC resonance Short out the capacitor in a RLC circuit with a light bulb resistance.
5L20.21 parallel AC resonance A capacitor and variable inductor tuned to resonate in parallel at 60 Hz have series light bulb current indicators.
5L20.21 parallel resonance A RLC series resonant circuit with a variable inductor and light bulb indicators.
5L20.22 RLC - resonance A variable inductor and capacitor in series with a lamp driven by 110 V AC. Short inductor or capacitor, vary both.
5L20.24 resonance at 60 Hertz The product of inductance in henrys and capacitance in microfarads should be 7.
5L20.26 LC parallel resonance An LC circuit is driven by coupling a second coil driven by an audio oscillator. Reference: AJP 36(1),x.
5L20.30 resonance curves on scope A crude but effective spectrum analyzer circuit for generating and displaying frequency response curves on an oscilloscope
5L20.31 RLC resonance plot on scope An x-y plot of the resonance curve is generated by mechanically driving a pot controlling the x axis of the scope by a chain to the tuning knob of the signal generator. Diagram, Picture.
5L20.40 coupled RLC circuits Two identical RLC circuits and a driving coil are coupled with a common core. The two are shown to resonate at the same frequency, then when both are operated simultaneously, there are two different frequencies at which resonance occurs. Diagram, Picture.
5L20.41 air coupled circuit Two coils are air coupled, one is driven by an audio oscillator and various capacitors are placed across the other coil while the output is monitored on an oscilloscope.
5L20.50 high voltage RLC ringing The secondary of a high voltage transformer is shunted across a spark gap, Leyden jars, and an inductor made of several turns of heavy copper all in series.
5L20.51 HF RLC resonance A 30 MHz 500W generator is coupled to a loop, light bulb, parallel plate RLC circuit and the capacitance changed to find resonance. Picture.

30. Filters and Rectifiers

5L30.10 bridge rectifier
5L30.10 bridge rectifier Plug in diodes on a Wheatstone bridge circuit board are used to demonstrate unrectified, half wave, and full wave rectification. Show on an oscilloscope.
5L30.10 bridge rectifier Half and full wave rectification with a plug in Wheatstone bridge board.
5L30.10 wheatstone bridge A Wheatstone bridge board with plug in elements.
5L30.10 rectifier circuit Diodes in a Wheatstone bridge configuration followed by two low pass filters.
5L30.11 bridge rectifier A circuit allows switching between unrectified, half, and full wave rectified configurations. A magnet bob pendulum and pickup coil provide a slow ac signal.
5L30.12 diode rectifier Use neon lamps to indicate rectification with a diode rectifier tube.
5L30.14 thermionic rectifier Kenotron type thermionic rectifier using a switch to change polarity of dc voltage.
5L30.16 very low frequency rectification Rectification can be demonstrated with a rotary potential divider and a vacuum tube in one of the standard circuits. Other stuff too.
5L30.20 blinky whirligig
5L30.20 blinky whirligig A small flashing light on the end of a string is whirled around.
5L30.20 blinky whirlygig An improvement on TPT,22(7),448, "AC made visible".
5L30.20 blinky whirligig Blinking neon bulb on a cord is swung around in uniform circular motion.
5L30.20 blinky whirligig Swing a light bulb around and take a picture of it with a fan strobed Polaroid
5L30.21 glow lamp swinger Swing a GE A9A or Chicago Miniature Ne-23 neon glow lamp in a 3 foot radius circle. Use as a persistence of vision demo by holding it still.
5L30.21 whirling glow lamp A two watt neon glow lamp is mounted on a hand rotator.
5L30.25 AC and DC with starch and iodine Drawing an electrode across a starch/iodine solution gives a solid line with dc and a dashed line with ac.
5L30.30 LC low pass filter Ammeters measure the current before and after a LC filter while an audio amplifier detects ac before and after as the frequency is varied.
5L30.31 current in an LC circuit Lamps are in series in each branch of an LC circuit to show current distribution as inductance is changed.
5L30.34 Fourier zeros LC circuit No energy is deposited in a resonant high Q circuit at f=n/pulse width. Circuit given.
5L30.35 mechanical analog of LC filter A string and pulley arrangement provides an analog of a parallel LC filter. Reference: AJP 14(5),318.
5L30.36 RLC filter A RLC parallel filter with each component individually switched is used to show the effect of each component on audio frequencies.
5L30.50 resonant cavity properties Identical ultrasonic transducers are bonded to opposite parallel faces of a solid medium. One is pulsed with a rf voltage at the transducer resonant frequency and the other is the receiver. The frequency adjusted to a Fabry-Perot resonance.
5L30.70 many circuits Nine simple circuits using diodes and transistors covering from rectifiers to a linear sweep generator.


10. Semiconductors

5M10.10 Hall voltage Measure the transverse potential of a large rectangle of biased N-doped germanium in a magnetic field.
5M10.10 Hall effect The transverse potential of a large rectangle of biased N-doped germanium is measured when inserted into a magnetic field.
5M10.10 Hall voltage Current is passed through a N doped germanium crystal while in a strong magnetic field and the voltage at the sides is monitored.
5M10.10 Hall effect Measure a voltage difference in a germanium sample perpendicular to the current flow when placed in a magnetic field. Picture Diagram, Construction details in appendix, p.1367.
5M10.10 Hall effect A Hall effect probe in a magnet, animation.
5M10.11 Hall effect magnet Apparatus Drawings Project No. 12: A small electromagnet for use with an indium-antimonide device.
5M10.12 Lorentz force on conduction electron A voltage is induced on a moving metal in a magnetic field.
5M10.15 an electron in a periodic potential The interaction of an electron with a crystal periodic potential is demonstrated with an air track cart mounted magnet moving past a magnet array.
5M10.19 model of a semiconductor A model made of pegboard and balls that shows a hole moving along a preselected path.
5M10.20 hot point probe A hot point probe consisting of a soldering iron and a microammeter tests for the two types of conductivity.
5M10.30 color centers Electrons or holes are injected into a large transparent alkali halide crystal in an oven resulting in the formation of color centers. Pictures, Diagrams, References: AJP 25,5 ,306.
5M10.32 color centers Injection of electrons into a transparent potassium chloride crystal at high temperatures results in the formation of color centers. Pictures.
5M10.34 Shockley-Haynes experiment A difficult but worthwhile demonstration illustrates diffusion and drift phenomena.
5M10.40 Josephson weak link model A rigid pendulum and aluminum disc are mounted on a shaft driven by a weight hanging on a thread wrapped around the shaft and damped by eddy currents.
5M10.50 diode
5M10.50 diode Positive and negative voltages are applied to a lamp in series with a diode.
5M10.60 PN junction Demonstrate a PN junction with a battery.
5M10.61 transistor curve tracer Circuits for constructing instruments to display transistor curves on an oscilloscope.
5M10.62 Fermi level model A model with ball bearings representing electrons and holes in Plexiglas representing states.
5M10.70 brillouin View a waveform on an oscilloscope through a cardboard with slots cut out.
5M10.71 brillouin/compass array
5M10.71 brillouin/compass array
5M10.90 transistor amplifier
5M10.90 transistor amplifier A transistor circuit board shows simple amplification.
5M10.92 integrated circuits Show transistors and integrated circuits including slides of integrated circuit blow ups.

20. Tubes

5M20.10 glow discharge
5M20.10 glow discharge Various discharge phenomena are described from atmospheric to high vacuum.
5M20.10 glow-discharge tube The pressure is reduced on a large tube while high voltage dc is applied to the electrodes.
5M20.10 gaseous discharge tube Pump down a long discharge tube to show Crookes' dark space, negative glow, Faraday dark space, striations, etc.
5M20.12 potential required for glow discharg Show the minimum voltage for a neon glow tube to discharge.
5M20.15 thermionic effect Use a tube to show the thermionic effect in a vacuum.
5M20.20 special purpose discharge tubes
5M20.20 special-purpose discharge tubes Gas discharge tubes for spectra, fluorescence of minerals, line tubes, paddle wheel, etc. are mentioned.
5M20.20 five cathode ray tubes Special tubes that demonstrate five properties of cathode rays.
5M20.25 electron beams A tube with a replaceable lime spot (or barium, strontium, and calcium oxides) hot cathode gives a brilliant beam. Diagram.
5M20.28 electron focusing Three types of focusing of the beam: residual gas, electrostatic, and magnetic.
5M20.30 gas filled tubes - two element type A circuit for demonstrating the mercury-vapor rectifier tube.
5M20.31 hot-cathode discharges The Tungar rectifier bulb and the phanotron mercury-vapor rectifier illustrate the role of cathode emission in discharge.
5M20.32 diode tubes The Welch demonstration power supply board is used to explain the theory of the diode tube.
5M20.35 thyratron tube The function of the grid in a discharge tube is shown with a thyratron.
5M20.36 gas filled tubes - grid controlled A circuit for demonstrating the thyratron tube.
5M20.40 three element tube curves A circuit for obtaining the characteristic curves of a triode.
5M20.41 "fresh air three electrode tube" Elements of a three electrode tube are placed in a bell jar.
5M20.42 three electrode tube model Steel balls represent electrons in a mechanical model of a triode. Picture.
5M20.43 three element tube - electrostatic A circuit for controlling the plate current of a three or four element tube.
5M20.44 the triode A circuit for demonstration the principles of a triode tube. Reference: AJP 23(9),384.
5M20.46 triode demonstrator unit Apparatus review of the Modern and Classical Instruments triode demonstrator board. (1961)
5M20.50 soap bubble model of tubes Soap bubbles moving through plates connected to a Van de Graaff generator simulate behavior of electron tubes. Picture.


10. Transmission Lines and Antennas

5N10.10 model transmission line
5N10.10 model transmission line - lamps
5N10.10 transmission of power Five 200 W bulbs connected in series along resistance wire.
5N10.10 model transmission line - lamps Six lamps are connected across two thin wires strung along the lecture bench.
5N10.10 voltage drop Voltages are measured successively across four 300 W bulbs.
5N10.13 drift velocity Move a Hall specimen perpendicular to the magnetic field in the opposite direction to the drift motion of carriers with exactly the drift velocity compensates for the Hall voltage.
5N10.15 HV line model
5N10.15 H.T. transmission A model transmission line with a lamp for a load that shows a loss unless transformers are used to boost voltage up and back.
5N10.16 power loss in transmission line A circuit demonstrates that the efficiency of power transmission increases with increased voltage. Variac, light bulb bank, meters, line resistance. Reference: AJP 21(2),110.
5N10.20 model transmission line - phases
5N10.20 model transmission line - phase A model transmission line is made of a series of sixty series inductors and shunt capacitors. An oscilloscope is used to show delay times and phase relationships.
5N10.21 wave propagation A demonstration of wave propagation in a toroidal transmission line with periodic variation of the wave phase velocity around the line.
5N10.22 wave propagation in aluminum Show amplitude decay and change in phase for waves propagating through an aluminum wedge or large sheet.
5N10.25 dispersion in non-inductive cable A model cable made of 150 series resistors and parallel capacitors shows delay and dispersion with meters at each end.
5N10.26 dispersion circuit A set of T filters with the input and output impedances matched are used to show dispersion of a short pulse.
5N10.27 dispersion of an EM pulse A microwave demonstration where as a sine wave burst is generated and the dispersion is observed in a slotted line waveguide with a sampling scope.
5N10.30 reflections in a coax
5N10.30 propagation in a coax A circuit using a wetted-contact mercury relay gives a pulse with a very fast rise time.
5N10.30 pulses on a coax Reflections in a coax using the Tektronix 545A delayed trigger.
5N10.30 propagation velocity in coax Using a square wave generator and oscilloscope, propagation time in 1', 20', and 40' of coax are compared. Diagrams
5N10.40 reflections in a coax
5N10.50 Lecher wires
5N10.50 Lecher wires A 80 MHz generator is coupled to a long transmission line and standing waves are demonstrated with neon and filament lamp probes.
5N10.50 Lecher wires Standing waves are set up on parallel wires from an 80 MHz generator.
5N10.50 Lecher wires Standing electromagnetic waves are coupled from an UHF oscillator to parallel wires.
5N10.50 Lecher wires Standing waves are generated on parallel wires by a radio transmitter. An incandescent bulb placed across the wires indicates voltage maxima.
5N10.52 Lecher bars Two six foot iron rods are used in a Lecher system with a fluorescent lamp detector.
5N10.55 microwave standing waves
5N10.55 microwave standing waves Measure the wavelength of a microwave transmitter by using a movable mirror to set up standing waves.
5N10.55 microwave standing waves Standing waves are set up between a microwave transmitter and a metal sheet. The receiver is moved between the two and the signal strength is displayed on a LED bar graph.
5N10.60 radiation from a dipole
5N10.60 radiation from a dipole
5N10.60 radiation from a dipole A flashlight bulb on a dipole detects radiation from an 80Mhz generator.
5N10.60 radio waves Show radiation with a 100 MHz dipole transmitter and hand held dipole receiver with a flashlight bulb detector.
5N10.61 radiation and polarization Polarization of radiation from a dipole antenna is checked with a hand-held dipole antenna with lamp indicator.
5N10.63 dipole radiation computer simulation R.H Good report on his Apple II dipole radiation simulation. Excellent and free.
5N10.65 directional antenna A directional antenna for use with a UHF oscillator.
5N10.70 waveguide normal modes Morie pattern type demonstration of normal modes in a waveguide.
5N10.80 EM vectors A dynamic model for demonstrating electric and magnetic vectors in an electromagnetic field. Picture, Diagrams.

20. Tesla Coil

5N20.10 induction coil The small handheld induction coil.
5N20.10 induction coil The small handheld induction coil.
5N20.10 induction coil A large induction coil, explained with the aid of animation.
5N20.12 induction coil A small Cenco induction coil.
5N20.13 induction coil All sorts of stuff on induction coils - producing high voltage from a DC source.
5N20.15 spark coil A discussion of the construction of a large spark coil and the effects of reversing polarity.
5N20.25 hand held Tesla and lamp Light a fluorescent lamp by touching with a hand held tesla coil.
5N20.25 hand held tesla and lamp
5N20.40 Tesla coil
5N20.40 Tesla coil
5N20.40 Tesla coil Description of a 500 KHz tesla coil.
5N20.41 continuous wave Tesla coil A tesla coil is coupled to an oscillator coil from A-32 or A-36.
5N20.42 Tesla coil Directions for building a Tesla coil and many demonstrations possible with it are described.
5N20.43 Tesla coil Directions for building a Tesla coil (Oudin coil when one end is grounded) that will give a thirty inch spark.
5N20.44 Tesla coil Pictures of two Tesla coils. References: Popular Science, Jan 1946, pp 191-194; Popular Science, June 1964, pp 169-73.
5N20.50 glowing fluorescent lamp
5N20.50 glowing fluorescent lamp
5N20.50 fluorescent light in radiation field A fluorescent light bulb is held in the Tesla coil radiation field.
5N20.50 Tesla coil Light a fluorescent tube at a distance, show the skin effect.
5N20.55 tesla coil and spinner
5N20.55 electrodeless discharge Hold a bulb of a gas at low pressure near a Tesla coil.
5N20.60 skin effect
5N20.60 skin effect
5N20.60 high frequency currents The skin effect carries enough current to light a bulb held in the hands.
5N20.70 betatron action An inductive coil replacing the high voltage transformer in the Tesla coil will give a visible beam in a partially evacuated glass bulb.
5N20.75 Tesla coil and spinner
5N20.75 space charge from high freq. corona Discharge a negatively charged electroscope with air blown from a Tesla coil corona.
5N20.80 Tesla coil and pinwheel Place a pinwheel on the secondary of a tesla coil.

30. Electromagnetic Spectrum

5N30.10 project the spectrum Project white light through a high dispersion prism.
5N30.10 projected spectrum with prism White light is projected through a high dispersion prism.
5N30.10 project the spectrum with prisms The optical path for projecting a spectrum using glass or liquid filled prisms.
5N30.10 project the continuous spectrum A carbon arc or concentrated filament lamp is used as a source with prism optics.
5N30.10 white light with prism Project a slit of light through a prism or hollow prism filled with carbon disulfide.
5N30.15 ultraviolet spectrum A carbon arc is projected through quartz optics and prism to a screen of half white paper and half fluorescent paper.
5N30.30 microwave transmitter & receiver
5N30.30 microwave transmitter & receiver A 12 cm transmitter and receiver are demonstrated.
5N30.30 microwave homebrew - 13 cm Build a high quality source and detector for $25. Explicit instructions.
5N30.30 microwave unit A LED bar graph indicates signal strength as a microwave transmitter is rotated around a receiver and as the beam is blocked by a metal sheet.
5N30.31 microwave wavelength by phase diff. Listen for minima as a second transmitter is moved back and forth a wavelength.
5N30.33 microwave resonance A modulated signal from a HP 616A generator is passed through a cavity to a detector with provisions to modify the cavity.
5N30.40 penetration of X-rays Use the ionization method with an electroscope to show penetration of X-rays.
5N30.41 absorption coefficents Show the thickness of various materials needed to cut the intensity of a beam in half.
5N30.50 IR camera and remote control device
5N30.50 IR from remote control device
5N30.50 water attenuation of microwaves A plexiglass box between the transmitter and receiver has no effect until filled with water.
5N30.50 microwave absorption Place dry and wet cloths in the microwave beam.
5N30.52 IR control devices