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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



To demonstrate electromagnetism.


The battery magnet has a very smooth surface and once energized is extremely hard to pull apart. If challenged, students will try in vain to seperate the two pieces.

The electromagnet is wound with four 0.0135" diameter copper wires in parallel. The length of each wire is from back edge of Rm. 203 big bench to last step just outside back door. The resistance of each wire is about 4.5Ω. If the magnet seems weaker than normal, it is possible either the battery is low or one of the wires is broken.


Note: We measured the impedance, inductance and current draw for this electromagnet assuming a 9V battery that has about 8-9V starting voltage.
  • Z = 6 Ω
  • L = 2 mH
  • I = 1 A


  • 9 V battery pack