Magnetic Materials

PIRA classification 5G

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.

5G10. Magnets

PIRA #

Demonstration Name

Abstract

5G10.10

magnet assortment

5G10.14

strong magnets

Various strong magnets are shown.

5G10.16

permanent magnets

Pick up nails with a cobalt steel magnet. Also - levitation, elastic collisions.

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

Show a magnet attracts nails, break it and repeat.

5G10.30

magnet and non-magnet

Two bars look alike, one is a magnet and the other is not. 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

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.

5G20. Magnet Domains & Magnetization

PIRA #

Demonstration Name

Abstract

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.

Magnetic domains in the core of a small coil can be heard flipping as a magnet is moved by using and an audio amplifier.

Insert various cores into a coil connected to an audio amplifier and spin a magnet around it.

Stretch a iron-nickel alloy wire through a coil and bring a magnet close to demonstrate sudden simultaneous magnetization.

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.

A soft iron core inserted in a small coil connected to the input of an audio amplifier.

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

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 domains

An array of small compass needles shows domain structures.

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

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

magnetic induction in earth's field

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.

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

Iron filings stick to a permalloy bar held parallel to the earth's magnetic field but fall off when it is held perpendicular.

5G20.56

permalloy rod

Hold a permalloy rod near a compass needle.

5G20.60

magnetization and demagnetization

Place an iron core in a solenoid. Magnetize with direct current and demagnetize by reducing alternating current to zero.

5G20.61

magnitizing iron by contact

Stroke a nail on a permanent magnet and it will pick up iron filings.

5G20.62

demagnitizing iron by hammering

Magnetize an iron bar in a solenoid, then pound it to demagnetize.

5G20.70

electromagnet

A simple electromagnet.

5G20.71

electromagnet

An electromagnet with 25 turns of wire and one dry cell can lift over 200 lbs.

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

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.

5G30. Paramagnetism and Diamagnetism

PIRA #

Demonstration Name

Abstract

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

Liquid oxygen is trapped in a strong magnetic field 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.

5G40. Hysteresis

PIRA #

Demonstration Name

Abstract

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

Water is boiled by magnetic hysteresis waste heat.

5G45. Magnetostriction and Magnetores

PIRA #

Demonstration Name

Abstract

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

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

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.

5G50. Temperature and Magnetism

PIRA #

Demonstration Name

Abstract

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 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

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

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

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.

Demonstrations

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