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Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography


Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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 Electric Fields And Potential
 Current and Resistance
 Electromotive Force And Current
 DC Circuits
 Magnetic Materials
 Barkhausen Effect
 Diamagnetic Levitation
  video  - Hysteresis
 Curie Point
 Meissner Effect (diamagnetic levitation)
 Complex Circuits
 Semiconductors And Tubes
 Transmission Lines and Antennas

Barkhausen Effect


An audible demonstration of the sudden alignment of magnetic domains in a ferrous material.


Three rods are supplied: copper, aluminum and iron. Only iron, being a ferrous material will exhibit the effect. place a rod into the coil and rotate the magnet in front of the rod. Each time a domain flips, the change of the magnetic field in the coil causes a small voltage spike which is picked up in the amplifier. As the magnetic field is reversed, a hissing sound is heard from the amplifier. This is the sound of the flipping magnetic domains in the material.


use microphone preamp, Low Z input. Needs a lot of gain.


  • Speaker
  • Aluminum rods
  • Audio Amplifier
  • Iron Rod
  • Barkhausen effect apparatus
  • copper rod