E&M (5F) - DC Circuits E&M (5H) - Magnetic Fields and Forces

## Magnetic Materials

PIRA classification 5G

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

# 5G10. Magnets

 PIRA # Demonstration Name Subsets Abstract 5G10.10 Magnet Assortment pira500 Pull out an assortment of magnet to show and play with. 5G10.14 Strong Magnets Pull out some very strong magnets to shown. 5G10.15 Lodestone Show that the lodestone attracts small nails and can deflect a compass needle. 5G10.16 Lodestone Supended pira1000 A large lodestone or magnetite 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 pira200 A broken magnet still exhibits north and south poles. 5G10.30 Magnet and Non-Magnet pira1000 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 Create a 4-pole bar magnet. How to induce four poles in a knitting needle, the same poles at each end. 5G10.36 No Pole Magnet pira1000 Make a circularly polarized magnet in a steel ring and then break it in half. 5G10.50 Magnetic Interactions pira1000 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. -or- When a coil around the dish is energized, the magnets move to the lowest energy configuration. 5G10.55 Gauss Accelerator - Gauss Rifle A Gauss rifle made from 3 square neodymium magnets and 1 inch ball bearings. Add two more stages of magnets and balls to observe an increased effect. 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 Subsets Abstract 5G20.10 Barkhausen Effect pira500 Insert various cores into a coil (like: nylon, brass, copper, soft iron, steel, and hard stee) that is attached to an audio amplifier. Listen to the staic as a strong magnetic is moves close to the coil to demonstrate sudden simultaneous magnetization 5G20.15 Spin-Flop Transition Model A mechanical model of the spin-flip transition in antiferromagnets. 5G20.20 Ferro-Optical Garnet pira500 View a microscope slide of garnet crystals between crossed polaroids with a color TV on a microscope as the megnetic field in coil near the slide is changed. 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 Domain Models pira200 An 2-D array of small compass needles shows domain structures. Helmholtz coils optional. 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 pira1000 Create a chain of nails that is supported by a strong magnet, each nail 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 pira500 Hammer a soft iron bar held parallel to the field of the earth. However a bar of permalloy is magnetized by simply holding it in the earth's field. 5G20.55 Permalloy Bar pira500 Iron filings stick to a permalloy bar when held parallel to the earth's magnetic field but fall off when it is held perpendicular. 5G20.56 Permalloy Bar Hold a permalloy bar near a compass needle. 5G20.60 Magnetization and Demagnetization pira1000 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 pira1000 Magnetize an iron bar in a solenoid, then pound it to demagnetize. 5G20.70 Electromagnet pira500 A simple electromagnet with core will pickup nails. {ie. 5H25.25} 5G20.71 Electromagnet pira1000 An electromagnet with 25 turns of wire and one dry cell can lift over 200 lbs. 5G20.72 Large Electromagnet pira1000 This magnet is made with ~3000 turnsand carries 25 amps. 5G20.73 Magnetically Suspended Ball pira1000 Useing two large alternating current magnet coils that produces a magnetic field of a shape and strength that can levitate an hollow aluminum ball or cyclinder 5G20.74 Magnetic Circuit pira100 An iron loop with a coil on one side, a flux meter on the other, and a removable section for substituting various materials. 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. 5G20.76 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 Subsets Abstract 5G30.10 Paramagnetic and Diamagnetic pira200 Small samples of bismuth, aluminum, glass, and crystals are inserted between the poles of a large electromagnet. 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. 5G30.16 Dollar Bill Attraction A dollar bill is attracted by a magnet. 5G30.20 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 solution A paramagnetic body is suspended in a paramagnetic solution. Repeat same with diamagnetic. 5G30.35 Diamagnetic Grapes Observe the diamagnetic or paramagnetic properties of common items such as grapes, rosin, salt, aluminum foil, etc., using a a neodymium magnet and a sensitive pivot. 5G30.40 Diamagnetic Water Cover a neodymium magnet with about 1 mm of water in a petri dish. The diamagnetism of water can be easily observed. 5G30.45 Diamagnetism of Pyrolytic Graphite A diamagnetic levitator using 2-D array of 1/4 inch square neodymium magnets (some 200 magnets) and a thin piece of pyrolite graphite 5G30.50 Diamagnetic Levitation of Graphite Small neodymium magnet levitating between two slabs of pyrolite graphite. 5G30.55 Diamagnetic Bismuth Place a bismuth sample on an electronic balance. The balance will show a positive "mass" when a neodymium magnet is brought near the top.

# 5G40. Hysteresis

 PIRA # Demonstration Name Subsets Abstract 5G40.10 Hysteresis Loop pira500 Show the hysteresis loops for laminated steel and ferrite cores as saturation is reached on an oscilloscope. 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 pira1000 Water is boiled by magnetic hysteresis waste heat.

# 5G45. Magnetostriction and Magnetores

 PIRA # Demonstration Name Subsets Abstract 5G45.10 Magnetostrictive Resonance pira1000 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 pira1000 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 pira1000 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 Subsets Abstract 5G50.10 Curie Point pira200 Iron under magnetic attraction is heated until it falls away. Upon cooling it is again attracted. 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. 5G50.12 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 Nickel pira1000 A Canadian nickel or old US nickel is attracted to a strong magnet. Falls away when it is heated with a torch. 5G50.16 Nickel Hysteresis Surface Pictures of a 3-D HMT hysteresis surface for nickel. 5G50.20 Magnetic Heat Motor pira1000 A thin strip of magnetic alloy (or Monel tape) 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. 5G50.22 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 pira1000 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 pira200 Cool a superconductor YBCO and a magnet floats over it due to magnetic repulsion. 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 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.

fw: MagneticMaterials (last edited 2020-07-01 23:13:34 by srnarf)