Electricity & Magnetism

EL-01

Producing Static Charge

Electrostatics

A) Rub balloon on yourself or on fur. Make it stick to you or wall. Make hair stand up. Touch to scope and see deflection.
B) Rub fur on rubber rod, place rod on scope, and see deflection.
Rub silk on glass rod, place rod on scope, and see deflection cancelled. Do it again and see deflection. Test this first!
C) Rip scotch tape from roll, touch to scope (also works w/plastic wrap) .

Place suspended PP ball on overhead projector.

A) Rub fur on rubber rod then bring rod near suspended pp ball. It attracts and then repels after touching.

Glass, plastic and rubber rods

Fur, wool, and silk cloths

Electroscope

Balloons

Metal-painted ping pong balls

Small lab stand

Scotch tape

Opposite Charges Attract

Like Charges Repel

EL-02

Induced Charge

Charged Attracts Neutral 1

Balance beam on watch glass.
Start beam normal to the audience (deflection is most obvious this way)
Charge rod (fur and rubber works best).
Hold near end of beam.

Watch it rotate.

Glass, plastic and rubber rods

Fur, wool, and silk cloths

4' long wooden 2x4 beam

Watch glass

EL-03

Induced Charge

Charged Attracts Neutral 2

Beforehand: Wrap fur around pen, secure with rubber band, place in pocket (so the pen is easily removable).

Place spoon on overhead.

Balance knife on spoon.
Pull pen from pocket (rubbing it against the fur), hold near knife, and make it rotate.
Explain the trick!

Small piece of fur

Pen

Plastic knife and spoon

Rubber band

EL-04

Induced Charge

Electroscope

Charge rod, hold it near the electroscope plate, and scope needle deflects.
Ground the electroscope frame and the needle undeflects.
Move rod away and the needle deflects.

Scope is charged by induction!

Glass, plastic and rubber rods

Fur, wool, and silk cloths

Projection electroscope

Ground wire

Watch Video 1

Watch Video 2

EL-05

Electric Field and Electrostatic Machines

van de Graaff

A) Bring grounded dome near VDG.
Throw big sparks (more impressive with room lights off).
B) Bring a grounded lightning rod near the dome (no more sparks).
C) Place stack of pie plates on VDG dome. Watch them fly off one by one.
D) Place a cup of rice krispies on the VDG dome and watch them fountain!
E) Place whirlygig on vdg and watch it whirl.
F) Hold bulb (near the end but not at it) with the other end pointing toward theVDG. It lights up. If it is held tangent to thedome, it won't light. Why?

van de Graaff generator

Plastic stool
Whirly-gig

Pie plates

Rice krispies in plastic cup

Broom

Second dome (groundable to VDG ground)

Llightning rod (groundable to VDG ground)

Small (but not compact) fluorescent bulb

Van de Graaff - Manually Powered

Van de Graaff - Motorized

Lightning Rod

Cereal Fountain

Fluorescent Light Bulb

EL-06

Dipoles and Induced Charge

Electric Dipole

Hold dipole pointing toward the VDG with the conductor connecting the two balls.
While it is still pointing (and the VDG is on) remove the conductor.
The dipole is now charged by induction.
Walk around the VDG.

One end of the dipole will always rotate to point toward the VDG.
This demonstrates:

A) Charging by induction

B) The torque on a dipole in an E field

C) The direction of the E field around the VDG

van de Graaff generator

Two metal balls on ends of wooden dowel (dipole) suspended by thread from a plastic rod

Short metal conductor or wire

Labels for each ball

EL-07

Electric Field

Hair Raising

Get volunteer to stand on plastic stool.
Have them place hands firmly on VDG.
Turn it on and wait for the hair to stand up.
Must turn off VDG and ground it before volunteer should let go.

van de Graaff generator

Plastic stool

EL-08

Induced Charge

Conductive Spheres

Place conductive spheres touching.
Charge rod.
Bring rod near one ball.
Separate balls.
Touch to electroscope to show that they are charged.

Glass, plastic and rubber rods

Fur, wool, and silk cloths

2 PASCO conductive balls on posts

Electroscope

EL-09

Induced Charge

Bouncing Ball

Place conductive ping-pong ball betweenVDG and grounded dome.
Turn on VDG.
Watch ping-pong game!

van de Graaff generator

Extra grounded dome

Metal painted ping pong ball suspended by two threads from a lab stand arm

EL-10

Electric Field and Electrostatic Machines

Wimshurst Machine

Crank the handle to build charge.
Cause sparks with the terminals.
Increase capacitance of machine by using Leyden jars.

Wimshurst Machine

Leyden jar

CI-01

Current

Light the Bulb

Distribute to the class.
Ask them to light the bulb.
Warn them that if the wire gets hot, they are doing something wrong!

Lots of light bulbs, batteries, and wire
(3-4" insulated wire with the ends stripped)

CI-02

Circuit Analysis

Car Battery and Bulbs

Show complete circuit.
Light one bulb.
Show series and parallel circuits.
Show bird on power lines.

Car battery with tall terminals

3 light bulbs in bases with wires and clip leads

Bird on a Wire

Series

Parallel

Series vs. Parallel

CI-03

Circuit Analysis

Circuit Boards

Show boards.
Challenge class to predict results:
1) Which is brighter, parallel bulbs or series bulbs?
2) What happens to the bulbs when the switch is closed (and shorts bulb B)?
3) Rank the 5 bulbs in order of brightness

Five premade circuit boards using D batteries and small bulbs:

1) Series vs parallel

2) Series and Parallel Combination

3) 5 bulb conundrum

4) circuit conundrums

5) circuit conundrums

Circuit 2

Circuit 3

Circuit 4

CI-04

Battery

Fruit Battery

Connect leads to fruit.
Clock now works .

Fruit battery

Apple

CI-05

Series Circuits

Bulbs in Series

Turn on power supply.

Close or open side connections to take out or add in more bulbs.

Light bulbs in series connection

Power supply

MA-01

Magnets

Magnets

See what the magnets pick up.
Charge the balloon to show it sticks to you.

Show the magnet does not pick it up.

Various magnets

Various materials to pick up (Fe, Al, plastic, wood, balloon)

MA-02

Forces on Magnets

Rotating Magnets

Show attraction and repulsion.

2 small cylindrical magnets

2 rotating magnet stands

MA-03

Magnetic Fields

Display Compass

Show that the compass points North.
Affect compass with other magnets.

Compass needle in clear plastic case for overhead projection

Note: Fill compass case with water for dampening.

MA-04

Magnetic Fields

Magnetic Field 1

Place magnet under tray on overhead.
Sprinkle filings gently.
Tap to realign.

Bar magnet

Plastic tray

Iron filings

MA-05

Magnetic Fields

Magnetic Field 2

Shake tray to redistribute filings.
Place magnet underneath.
Wait.

Bar magnet

Plastic tray with internal iron filings in viscous fluid

MA-06

Magnetic Fields

Magnetic Field 3

Place bar magnet on plate on overhead projector.

Bar magnet

Array of small compass needles

MA-07

Magnetic Fields

3D Magnetic Field

Too small for large classes.

Bar magnet

3D B-field visualizaer

MA-08

Fields and Currents

Magnetic Field Around Wires 1

Connect configuration to power supply.
Run a LOT of current.
Sprinkle filings.

Wire, loop and solenoid configurations on plastic trays

Power supply

Iron filings

MA-09

Fields and Currents

Magnetic Field Around Wires 2

Wrap the wire around the compass 2 or 3 times.
Connect the wire battery.
See the compass needle deflect.

Compass

Wire

D battery

MA-10

Force on Current Carrying Wires

Jumping Wire

Connect power supply to jumping wire setup.
Turn on power supply (high current).
Operate knife switch.

Jumping wire setup

Power supply

MA-11

Force on Current Carrying Wires

Small Jumping Wire

Place C magnet with gap horizontal.
Suspend loop in gap and connect wire to battery.
See deflection.
Reverse B or I.

C-magnet

Wire

9 volt battery

MA-12

Force on Moving Charges

Deflect e Beam 1

Hold portable Tesla coil near end of tube.
Show e-beam on phosporescent screen.
Hold magnet near tube to show deflection.

Show deflection reverses when the field reverses.

Electron beam tube

Tesla coil

Magnet

MA-13

Coming Soon

Force on Moving Charges

Deflect e Beam 2

Hold portable Tesla coil near end of tube.
Show e-beam on phosporescent screen.
Place solenoid above e-beam.
Turn on power supply and use switch to choose direction of current.
Show that current running different directions deflects the e-beam different ways.

Electron beam tube

Tesla Coil

Solenoid

Power Supply

MA-14

Fields and Currents

Build an Electromagnet

Challenge students to build an electromagnet.

Iron nails (10 or 12 penny)

20-24 guage insulated wire (3 feet long)

Sandpaper

Battery

Paperclips (one set per 2-3 students)

MA-15

Magnetic Fields

Constancy of Magnets

Set the magnet in the middle.

Aim all 4 needles at the magent.

Needles stay suspended in air.

Magnet stand

4 sewing needles

Fishing Line

MA-16

Magnetic Fields

Right Hand Rule

Pass out both types of bolts to students.

Discuss right-handed versus left-handed rules.

Right-handed and left-handed nuts and bolts

MA-17

Magnetic Fields

Ferromagnetic Fluid

Set up the tube of ferro-fluid and aim the document camera at it.

Bring the magnet close to view spikes.

Easily drag around the fluid with the magnet.

Neodymium magnet

Tube of ferromagnetic fluid

Portable Elmo document camera

MA-18

Diamagnetism

Diamagnetic Levitation

Set the magnet between the plates of cobalt and it will float.

Poke with a pencil to send it spinning.

Note: Set up beforehand to ensure the plates are spaced properly.

Diamagnetic levitation stand

Small neodymium magnet

Portable Elmo document camera

MA-19

Force on Current Carrying Wires

Newton's Bulb

Turn on the bulb then bring the magnet near it.

The wire inside the bulb will oscillate rapidly.

(Warning: Do not use too strong of a bulb or bring the magnet too close. Filament will snap from large oscillations.)

Newton's bulb

Strong magnet

MA-20

Magneto Hydro Dynamics

Small Scale MHD

Set up MHD kit according to included instructions.

Show on overhead projector or use Elmo camera.

MHD kit

Vinegar

Food coloring

9V battery

MA-21

Fields and Currents

Lifting Magnet

Show that the two halves do not stick together.
Insert battery.
Have students try to pull it apart or hang from ceiling.
(Should be able to hold up to 200 lbs. on a single D battery.)

Lifting magnet kit

D-cell battery

Two ropes

MA-22
 

Force on Current Carrying Wires

Electric Swing

Connect power supply to electric swing and briefly turn on.

Swap the power supply leads to cause it to swing the other direction.

Electric swing

Stand for the swing

Banana-gator leads

C-shaped magnet

MA-23
 

Magnetic Force

Magnetic Accelerator

Place 3 ball bearings and magnetic sphere on track.

Roll 4th bearing towards the others to launch another bearing.

Magnetic accelerator track.

4 ball bearings

Sperhical neodymium magnet

MA-24
 

Magnetic Force

Magnetic Putty

Put a magnet in the putty and watch the putty "crawl" towards it.

Magnetic putty

Neodymium magnet

MA-25
 

Magnetic Force

Levitron

Spin up the levitron, carefully raise the levitron into position, and pull away the platform.

Will need time to set this demo up as it needs fine adjustments to work reliably.

Levitron apparatus.

Electromagnetic Force Demonstrator

Genecon Hand Crank or DC Power Supply

MI-01

Induction

DC Motor

Connect it up.
It spins!
Be careful to use as little current as possible.

DC motor
Power supply

2 banana-aligator clip leads

MI-02

Induced Current

Magnetic Induction 1

Display galvanometer on overhead.
Wire it to the coil.
Push magnet in and out.

Large coil

Several bar magnets

Display galvanometer

2 banana-banana clip leads

MI-03

Coming Soon

Induced Current

Magnetic Induction 2

Push magnet through coil.

Discuss direction of current.

Coil with two LEDs

Magnet

MI-04

Magnetic Induction

Lenz's Tube

Get a student volunteer.
Show that both weights are identical.
Get student to drop one through (try to get them to choose the nonmagnetic one first).
Then have them drop the magnet.
Make sure you show that the tube itself is nonmagnetic.

Large Lenz's tube

Two identical weights (one magnetic, one not)

MI-05

Magnetic Induction

Lenz's Pendulum

Show pendulum swings freely.

Place magnet at bottom of swing, pull pendulum back, and let go.

Lucite pendulum stand with aluminum disk as pendulums

Large C magnet

Small

Large

MI-06

Magnetic Induction

Ring Shooter

A) Make the ring hover by placing it at the top of the iron core. Ask the class how much electromagnetic force holds it there (assuming it weighs 1 N).
B) Shoot Al ring high in the air. How much EM force was exerted on that ring?
C) Ask class what will happen with the slotted ring?
D) Then ask about the plastic ring.
E) Ask for a strong volunteer to hold down the ring while the ring shooter is on. See how much force is required. It gets HOT!

Ring shooter

Various rings (solid Al, slotted Al, plastic, iron)

Ring Shooter

Iron Core

MI-07

Induction

Motor/Generator

Connect motor to power supply.
Watch it spin.
Connect motor to galvanometer, make it spin, and generate current.

Electric motor

Galvanometer

Power supply

MI-08

Coming Soon

Induced Current

Single Wire Induction

Move single loop of wire through magnet to induce current.

Wire

Galvanometer

C magnet

MI-09

Induced Current

Hand Crank Generator

Crank generator

Light bulb

Hand crank generator with light bulb

MI-10

Induced Current

Pistol Generators

Attach generator to bulb, crank, and light the bulb.
Attach generators to each other.

Crank one the other turns.

One is the motor the other is the generator.

2 pistol-type generators

Light bulbs

MI-11

Induced Current

Wireless Bulb

Push button and the bulb lights.
Light is brighter when held lower on the ring shooter.

Ring shooter

Coil and bulb

MI-12

Induced Current

Primitive Telegraph

Connect one coil to the galvanometer.
Connect the other coil to the DC supply and the switch.
Place the coils face to face without the core.
Tap the switch showing the deflection of the meter.
Redo with iron core lying through both coils.

2 large coils

Iron core

Galvanometer

Switch

DC power supply

MI-13

Transformers

Transformer

Attach the two coils to the iron core. Attach the primary coil to the variac.
Attach the secondary to the AC voltmeter.
Compare the display voltages with those expected.
Vary the number of turns in the secondary.

PASCO transformer and coils set

Variac

AC display voltmeter
(Can also do this with 1 and 2-loop coils made from regular wire.)

Magnetic Induction

Inverted Lenz's Tube

Invert the demo.

Watch the magnets fall at different rates.

Demo with three rods of different materials and ring magnets on the outside of the rods.

(Rods are wood, aluminum, brass, and copper.)

MI-15

Magnetic Induction

Two Coil 'Radio'

Connect coil to the speakers.

Connect the other coil to the music source.

Place the coils face to face without the core.

Play the music.

Should be able to hear music in the speakers when the coils are facing but not when they are far apart or perpendicular.

Redo with iron core lying through both coils. The music should be much louder.

2 large coils

MP3 player or equivalent

Powered speakers

Headphone jack -> two banana plugs cable

Speaker cable -> two banana plugs

Iron core

MI-16

Magnetic Induction

Induction Flashlight

Show the flashlight doesn't work.

Shake the flashlight.

Show that it now works.

Induction flashlight

MI-17

Magnetic Induction

D-Cell Electromagnet

Place battery in electromagnet and attach alligator clip.

D-Cell electromagnet

D-Cell Battery