Electromagnetic Induction

PIRA classification 5K

Grayed Demos are either not available or haven't been built yet

Please note that these tables have not yet been edited to match the equipment that is available within the UW-Madison lecture demo lab. There maybe many items listed within these tables that we either "can not do" or have available.

5K10. Induced Currents and Forces

PIRA #	Demonstration Name	Subsets	Abstract
5K10.10	Sliding Rail		Slide a bar up and down a set of rails through a bed of strong magnets that is attached to a galvanometer.
5K10.12	mu metal shield and insulator		The sliding rail with an insulated mu-metal shield still gives the same result.
5K10.15	moving wire with magnet		A wire connected to a galvanometer is moved in and out rapidly through the poles of a strong 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 and magnet	pira200	A magnet is moved in and out of a coil of wire attached to a galvanometer.
5K10.21	10/20/40 coils with magnet		Coils of 10, 20, and 40 turns are attached to a galvanometer.
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		Slap a coil attached to a flash blub with a 3" diameter neodymium magnet disc.
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	pira200	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.
5K10.31	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	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		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.
5K10.51	Modulated Coil		A 14 turn coil is connected to the headphone output of a radio, tape player, or CD player. Another identical coil connected to a mini amplifier with speaker can pick up the transmission. Use an iron core to enhance the effect.
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		the deflection of a ballistic galvanometer from a flip coil is compared to a standard flux. ie 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	earth inductor on oscilloscope		Subsititute an oscilloscope for the galvanometer and look at the induced voltage versus time.
5K10.63	rotating coil magnetometer		A motor driven coil of several hundred turns gives a different galvanometer deflection depending on the orientation. One can also display the signal coil on an oscilloscope.
5K10.65	Earth inductor jump rope		Play "jump rope" with a 50 foot extension cord or long wire attached to an oscilloscope or galvanometer. The cord must have an East-West alignment.
5K10.70	what do voltmeters measure?		Two identical voltmeters connected at the same points in a circuit around a long solenoid give different readings.
5K10.78	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.
5K10.81	radial homopolar generator		A variation on the axial field homopolar motor (Barlow's 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. A direct demonstration of Ampere's circuital law using a flexible toroidal coil.
5K10.90	electromagnetic can crusher/breaker		A large pulse of induced current in a soda can blows it apart.

5K20. Eddy Currents

PIRA #	Demonstration Name	Subsets	Abstract
5K20.10	Eddy currents in pendulum	pira200	A copper sheet and comb are swung through a large electromagnet.
5K20.11	magnetic brake		A heavy copper disk swings as a pendulum between the poles of an electromagnet.
5K20.15	eddy damped pendulum		A bar magnet suspended as a pendulum is damped as it swings over a copper plate.
5K20.20	falling plate		A heavy copper sheet is dropped through the poles of some strong magnets that are removoble.
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.
5K20.24	Cu Plates and magnet		large diameter neodymium magnet on a copper plate. Then cool the plate with liquid nitrogen and see what happens. Osheroff Demo.
5K20.25	Eddy current tubes	pira200	Drop a magnet and a dummy in glass and aluminum tubes, then switch. The magnet in Al falls slowly.
5K20.26	Faraday repulsion	pira200	Thrust the pole of a magnet in and out of a copper ring that is on a bifilar suspension.Showing forces due to the induced current.
5K20.30	jumping ring		A solid aluminum ring on the vertical transformer jumps while a split ring does not.Use LN2 to increase the current flow within the ring and an core extender.
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.

5K20.42	Arago's disk		A magnet suspended above a rotating horizontal copper disk will 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		A hollow aluminum ball rotates in a watch glass atop a shaded pole transformer.
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 crusher	pira1000	A large capacitor discharged into a low impedance coil of a few turns produces a magnetic field strong enough to crush or break an aluminum soft drink can.

5K30. Transformers

PIRA #	Demonstration Name	Subsets	Abstract
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	pira200	Various cores are interchangeable with the Leybold transformer. Voltages can be shown on the primary and secondasry coils of a dissectible 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		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		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		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	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.

5K40. Motors Generators

PIRA #	Demonstration Name	Subsets	Abstract
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		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		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		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	pira200	Use the double throw switch to connect the battery to the motor. the 500 gram mass will rise. Switch to to neutral and let the mass fall halfway. Switch to light bulb and bulb will light.
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/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		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.

Demonstrations

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