PIRA 200
Electricity and Magnetism

Rods and Fur
Rods and Pivot
Soft Drink Can Electroscope
Charging by Induction
Charge Propelled Cylinder
Van de Graaff Generator
Hair on End
Electric Field Lines
Faraday's Ice Pail
Radio in a Cage
Point and Ball with Van de Graaff
Parallel Plate Capacitor
Capacitor with Dielectrics
Short a Capacitor
Light the Bulb
Resistance Model
Wire Coil in LN2
Conduction in Glass

Electricity and Magnetism

5A10.10

ELECTROSTATICS

Producing Static Charge

Rods and Fur

 

Rub the wool felt cloth on the PVC rod to produce negative charge on the rod.

Rub the cellophane on the acrylic rod to produce positive charge on the rod.

Workshop Video

Electricity and Magnetism

5A20.10

ELECTROSTATICS

Coulomb's Law

Rods and Pivot

 

Rub both ends of a rod and center it on the pivot. Rub the PVC rod (negative charge) with the felt or the acrylic rod (positive charge) with the cellophane.

Rub one end of a second rod and hold its charged end near the end of the rod on the pivot.

Workshop Video

Electricity and Magnetism

5A22.25

ELECTROSTATICS

Electrostatic Meters

Soft Drink Can Electroscope

 

The tab of the soft drink can supports the electroscope leaves in this simple version.

Workshop Video

Electricity and Magnetism

5A40.10

ELECTROSTATICS

Induced Charge

Charging by Induction

 

Charging by induction with an electroscope for a charge indicator.

Electricity and Magnetism

5A40.20

ELECTROSTATICS

Induced Charge

Charge Propelled Cylinder

 

Set an empty soda can on the table so the open end faces the students. Pull the can forward with induced charge. Switch to the oppositely charged rod and repeat.

Workshop Video

Electricity and Magnetism

5A50.30

ELECTROSTATICS

Electrostatic Machines

Van de Graaff Generator

 

Have student stand on platform and place hand on top of VDG. Do not remove hand from the surface. Turn on the VDG and observe their hair.

Turn off the VDG. Use grounding wire attached to base of generator to discharge the sphere, then allow student to withdraw hand.

Place various equipment items in kit one at a time on top on the VDG and turn it on.

Electricity and Magnetism

5B10.10

ELECTRIC FIELDS AND POTENTIAL

Electric Field

Hair on End

 

Remove pointed metal items such as keys and microphones. Stand on the insulated stool. With the variable control fully counter-clockwise, turn the power on. Hold the pointed probe against the sphere while turning up the motor.

Place your other hand on the sphere before removing the probe. Do not remove your hand and stay away from anything metal. Allow yourself to charge up. Fine, clean, dry hair stands on end the best.

Try pointing at a student or the electrified strings.

To discharge without shocks, hold pointed probe against the sphere, remove other hand and turn off motor.

Electricity and Magnetism

5B10.40

ELECTRIC FIELDS AND POTENTIAL

Electric Field

Electric Field Lines

 

Bits of material suspended in oil align with an applied electric field. Several pole arrangements are shown.

Electricity and Magnetism

5B20.10

ELECTRIC FIELDS AND POTENTIAL

Gauss' Law

Faraday's Ice Pail

 

Charge the sphere several times by rubbing a charged rod on its surface. Touch the proof plane to the outside of the sphere and then to the electroscope. The electroscope charges, indicating there is a charge on the outside of the sphere.

Repeat the same test on the inside of the sphere. The electroscope does not charge.

Electricity and Magnetism

5B20.35

ELECTRIC FIELDS AND POTENTIAL

Gauss' Law

Radio in a Cage

 

Turn on the light and the radio. You should hear static that the radio picks up from the fluorescent light source. Place the Faraday cage over the radio and you hear nothing.

Workshop Video

Electricity and Magnetism

5B30.35

ELECTRIC FIELDS AND POTENTIAL

Electrostatic Potential

Point and Ball with Van de Graaff

 

Hold a ball close to a VDG and then bring a point close.

Workshop Video

Electricity and Magnetism

5C10.20

CAPACITANCE

Capacitors

Parallel Plate Capacitor

 

Change the spacing of a charged parallel plate capacitor while it is attached to an electroscope.

Workshop Video

Electricity and Magnetism

5C20.10

CAPACITANCE

Dielectrics

Capacitor with Dielectrics

 

Place a dielectric between the plates and push the plated against the dielectric. Turn on the power supply to charge the plates. Disconnect ground lead BEFORE turning the supply off. Slide the dielectric out of he plates and observe how the electroscope changes. Insert other dielectrics.

Workshop Video

Electricity and Magnetism

5C30.20

CAPACITANCE

Energy Stored in a Capacitor

Short a Capacitor

 

Turn on the power supply to charge the 5600 microfarad capacitor through the power resistor. Remove the leads from the capacitor without touching the binding posts. Short the posts with the shaft of a screw driver (not the tip).

Workshop Video

Electricity and Magnetism

5C30.30

CAPACITANCE

Energy Stored in a Capacitor

Light the Bulb

 

Turn on the power supply to charge the capacitor through the power resistor. Turn off the power and disconnect the power supply. To discharge the capacitor, connect to the light bulb only. Do not short the capacitor. The 60W bulb lights for about 3 seconds. A 7.5 W bulb lights for about 20 seconds.

Workshop Video

Electricity and Magnetism

5D10.40

RESISTANCE

Resistance Characteristics

Resistance Model

 

Ball bearings are rolled down an inclined bed of nail to simulate current flow in a wire.

Electricity and Magnetism

5D20.10

RESISTANCE

Resistivity and Temperature

Wire Coil in LN2

 

Set up as shown. Place the coil into the LN2. Watch the light bulb get brighter as the coil cools.

Electricity and Magnetism

5D20.60

RESISTANCE

Resistivity and Temperature

Conduction in Glass

 

A light bulb is smashed with a mallet and the filament is cut off. Then, the glass stem is heated with a blow torch.

Workshop Video

Electricity and Magnetism

5D40.10

RESISTANCE

Conduction in Gases

Jacob's Ladder

 

This is a step up transformer. CAUTION: LETHAL VOLTAGE

Turn on the power and the discharge will travel up the wires. The distance between the wires is the critical adjustment. The wires should not be moving.

This does not work will on humid days. Unplug after use so that students don't inadvertently play with it.

Workshop Video

Electricity and Magnetism

5E40.25

ELECTROMOTIVE FORCE AND CURRENT

Cells and Batteries

Lemon Battery

 

Copper and Zinc electrodes in a lemon are connected to a digital meter.

Electricity and Magnetism

5E50.10

EMF AND CURRENT

Thermoelectricity

Thermocouple

 

A voltmeter is connected to the iron wires of two copper-iron wire junctions hanging from a stand. Light the Bunsen burner and heat one of the junctions, watching the voltmeter. You can also immerse a junction in ice.

Electricity and Magnetism

5F10.10

DC CIRCUITS

Ohm's Law

Ohm's Law

 

Digital meters measure the current and the voltage in a simple circuit of a battery and resistor. The rheostat is adjusted so that the meters read the same, differing only by a factor of 1000. The battery pack contains six 1.5 volt batteries in series. Change the number of batteries in the circuit OR change the resistance and observe that the meters change proportionally.

Workshop Video

Electricity and Magnetism

5F15.35

DC CIRCUITS

Power and Energy

Fuse with Increasing Load

 

 A fuse wire will eventually fail when the load on the circuit is increased. 

Electricity and Magnetism

5F20.10

DC CIRCUITS

Circuit Analysis

Kirchhoff's Voltage Law

 

Measure the voltage at different places in the circuit and show that the sum is zero. There are many possible combinations of components.

Workshop Video

Electricity and Magnetism

5F20.50

DC CIRCUITS

Circuit Analysis

Series and Parallel Circuits

 

If the combined series and parallel boards are confusing, try the separate boards.

Workshop Video

Electricity and Magnetism

5F30.10

DC CIRCUITS

RC Circuits

Capacitor and Light Bulb

 

A 5600 microfarad 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.

Electricity and Magnetism

5G10.20

MAGNETIC MATERIALS

Magnets

Break a Magnet

 

A broken magnet still exhibits north and south poles.

Electricity and Magnetism

5G20.30

MAGNETIC MATERIALS

Magnetic Domains and Magnetization

Magnetic Domain Models

 

There are two types of arrays: 1) Coplanar to show domains and 2) non-coplanar (random orientation). Bring a magnet near each array.

Electricity and Magnetism

5G30.10

MAGNETIC MATERIALS

Paramagnetism and Diamagnetism

Paramagnetism and Diamagnetism

 

Paramagnetic and diamagnetic crystals are inserted between the poles of a large magnet or electromagnet.

Workshop Video

Electricity and Magnetism

5G50.10

MAGNETIC MATERIALS

Temperature and Magnetism

Curie Point

 

Iron under magnetic attraction is heated until it falls away. Upon cooling it is again attracted.

Electricity and Magnetism

5G50.50

MAGNETIC MATERIALS

Temperature and Magnetism

Meissner Effect

 

Place a magnet on warm superconducting disk to show how nothing happens, then remove. Add LN2 to the Styrofoam container holding the super conducting disk. When the boiling stops, the disk is cold. Use the plastic tweezers to place one of the magnets on the disk.  The magnet will float above the disk.

Workshop Video

Electricity and Magnetism

5H10.20

MAGNETIC FIELDS AND FORCES

Magnetic Fields

Oersted's Effect

 

Turn the compass needle so it is approximately parallel to the wire. Close the switch to send the current through the wire for about 5-10 sec. The compass will align itself with the magnetic field.

Workshop Video

Electricity and Magnetism

5H10.30

MAGNETIC FIELDS AND FORCES

Magnetic Fields

Magnet and Iron Filings

 

Sprinkle iron filings on the Plexiglas plate. Tap the Plexiglas to encourage alignment.

Workshop Video

Electricity and Magnetism

5H15.10

MAGNETIC FIELDS AND FORCES

Fields and Currents

Magnetic Field Around Wire

 

Sprinkle iron filings on the Plexiglas. Hold down the switch briefly connecting the bottom while tapping the Plexiglas to encourage alignment.

Workshop Video

Electricity and Magnetism

5H15.40

MAGNETIC FIELDS AND FORCES

Fields and Currents

Solenoid and Iron Filings

 

Sprinkle iron filings on the Plexiglas. Hold down the tap switch briefly connecting the bottom while tapping the Plexiglas to encourage alignment.

Workshop Video

Electricity and Magnetism

5H20.10

MAGNETIC FIELDS AND FORCES

Forces on Magnets

Magnets and Pivot

 

One magnet is centered on a pivot. Hold one end of the second magnet near one end of the magnet on the pivot. Repeat with the opposite end.

Workshop Video

Electricity and Magnetism

5H30.10

MAGNETIC FIELDS AND FORCES

Force on Moving Charges

Cathode Ray Tube

 

Plug in the cathode ray tube. Deflect the beam of the CRT by holding a permanent magnet near the edge of the tube. If the beam disappears, you are holding the magnet too close.

OR, deflect the beam by attaching a battery to the binding posts and adjusting the variable control knob.

OR connect the battery directly to the deflection plate terminals.

Workshop Video

Electricity and Magnetism

5H40.10

MAGNETIC FIELDS AND FORCES

Forces on Current in Wires

Parallel Wires

 

Two insulated wires hang from a frame. Turn on the switch. Wires will attract or repel each other. Turn off the switch and reverse the leads in the binding posts. Turn the switch on. Wires will repel or attract each other.

Workshop Video

Electricity and Magnetism

5H40.15

MAGNETIC FIELDS AND FORCES

Forces on Current in Wires

Interacting Coils

 

Hang two coils from a support rod. Connect the DC power supply so that the current is in the same direction in both coils and watch them attract. Connect the DC power supply in opposite directions in the coils and watch them repel. A good storage battery can be used instead of the power supply.

Workshop Video

Electricity and Magnetism

5H40.30

MAGNETIC FIELDS AND FORCES

Forces on Current in Wires

Jumping Wire

 

A long wire is coiled around one pole of a permanent magnet. Close the switch. The wire collapses into the magnet. Turn the coil over and repeat. The wire "jumps" out of the magnet.

Workshop Video

Electricity and Magnetism

5H50.10

MAGNETIC FIELDS AND FORCES

Torques on Coils

Model Galvanometer

 

A crude galvanometer with a large coil and magnet demonstrates the essentials.

Electricity and Magnetism

5J20.10

INDUCTANCE

LR Circuits

LR Time Constant on Scope

 

A plug in circuit board with a make before break switch for showing slow RL time constants on the oscilloscope.

Workshop Video

Electricity and Magnetism

5J20.20

INDUCTANCE

LR Circuits

Series or Parallel Lamps w/Inductor

 

Two lamps are used to indicate voltage across and current through a large electromagnet.  Do this with the iron core in and then with the iron core removed.

Electricity and Magnetism

5K10.20

ELECTROMAGNETIC INDUCTION

Inducted Current and Forces

Induction Coil and Magnet

 

Move the magnet in and out of the coil connected to the galvanometer.

Electricity and Magnetism

5K10.30

ELECTROMAGNETIC INDUCTION

Inducted Current and Forces

Mutual Induction Coils with 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.  Aluminum, laminated iron, and other solid iron cores are available.

Electricity and Magnetism

5K20.10

ELECTROMAGNETIC INDUCTION

Eddy Currents

Pendulum in Big Electromagnet

 

Show that a solid copper plate swings between the poles of the electromagnet when the power is off. Turn on the power. Displace the pendulum and let it swing. It stops dead between the poles. Repeat with the slotted plate, ring and slit ring. Cannot leave the power on.

Workshop Video

Electricity and Magnetism

5K20.25

ELECTROMAGNETIC INDUCTION

Eddy Currents

Magnets and Tubes

 

Drop magnets simultaneously down the copper and stainless steel tube. It takes approximately 3 seconds for the magnet to fall through the three foot copper tube. Dummy magnets are also available.  Aluminum tubes will also show damping.

Workshop Video

Electricity and Magnetism

5K20.26

ELECTROMAGNETIC INDUCTION

Eddy Currents

Faraday Repulsion Coil

 

A magnet is inserted and withdrawn from a solid and split ring on a bifilar suspension.  It is possible to "pump" the solid ring.

Electricity and Magnetism

5K30.20

ELECTROMAGNETIC INDUCTION

Transformers

Dissectible Transformer

 

Voltages can be shown on the primary and secondary coils of a dissectible transformer.

Electricity and Magnetism

5K40.40

ELECTROMAGNETIC INDUCTION

Motors and Generators

Motor / Generator

 

Use the double throw switch to connect the battery to the motor. The 500 gram mass will rise. Switch to neutral and let the mass fall halfway down to build up speed. Switch to light bulb and bulb will light.

Wokshop Video

Electricity and Magnetism

5L20.20

AC  CIRCUITS

RLC Circuits - AC

RLC Resonance

 

The light bulb in a RLC circuit glows when the inductor core is moved through resonance.

Also, RLC resonance shown on an oscilloscope.

Electricity and Magnetism

5N10.80

ELECTROMAGNETIC RADIATION

Transmission Lines and Antennas

EM Vectors

 

A dynamic model for demonstrating electric and magnetic vectors in an electromagnetic field.

Electricity and Magnetism

5N20.10

ELECTROMAGNETIC RADIATION

Tesla Coil

Induction Coil

 

Turn on the Tesla coil. Take the spectra tube and hold it within 2 feet of the Tesla coil. Vary the distance. Do the same thing with the fluorescent tube. Using the grounding wire on the end of the tube can help avoid unpleasant shocks.  Discuss shocks vs. burns and high frequency AC. 

Workshop Video

Electricity and Magnetism

5N30.10

ELECTROMAGNETIC RADIATION

Electromagnetic Spectrum

Projected Spectrum w/Prism

 

White light is projected through a high dispersion prism and onto a screen.

Workshop Video