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[:Demonstrations:Demonstrations]

[:Instructional:Home]
[[Demonstrations]]

[[Instructional|Home]]

Magnetic Fields and Forces

PIRA classification 5H

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.

5H10. Magnetic Fields

PIRA #

Demonstration Name

Abstract

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

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

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

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

Vary the gap of a magnet and measure the field with a gaussmeter.

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

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

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.

5H15. Fields and Currents

PIRA #

Demonstration Name

Abstract

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

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

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

5H15.25

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

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.

5H20. Forces on Magnets

PIRA #

Demonstration Name

Abstract

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

5H20.20

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

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 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 power - magnetism

Equipment shows the force between two dipoles varies as the inverse fourth power of the separation. Pictures.

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.

5H25. Magnet/Electromagnet Interaction

PIRA #

Demonstration Name

Abstract

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

Place a bar magnet in a vertical transformer and apply DC with a tap switch.

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.

5H30. Force on Moving Charges

PIRA #

Demonstration Name

Abstract

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 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

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

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

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

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.

5H40. Force on Current in Wires

PIRA #

Demonstration Name

Abstract

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

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

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

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

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 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 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.

5H50. Torques on Coils

PIRA #

Demonstration Name

Abstract

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

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

5H50.30

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.

5H50.31

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

5H50.30

interacting rotating coils

Add abstract in Handbook.FM

Demonstrations

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