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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
  video  - Van de Graaff Generator
  video  - Electrostatic Bell
 Electric Lines of Force
 Electrostatic Motor
  video  - Electric Fields
  video  - Gauss' Law
 Radio in Faraday Cage
  video  - Fluorescent Bulb in Faraday Cage
  video  - Lightning Rod
  video  - Electric Wind
 Ionic Drive
  video  - Smoke Precipitator
 Current and Resistance
 Electromotive Force And Current
 DC Circuits
 Magnetic Materials
 Complex Circuits
 Semiconductors And Tubes
 Transmission Lines and Antennas

 video  - Electric Fields


To show the electric lines of force in different electric fields.


centered image

Cover bottom of bowl with about 1/4 inch of oil and felt mixture and place on overhead projector. Put clamps on edge of bowl and insert electrodes of your choice. Connect wires from clamps to power supply and turn on. It takes about 10-15 seconds for the supply to generate high voltage. The felt will become polarized and migrate along the electric lines of force showing clearly the geometry of the field.

The felt and oil mixture should be remixed in the bowl before attempting a new electrode configuration


Using a metallic mixing tool (there is a strip of aluminum for this purpose) helps to reduce charge buildup on the apparatus during consecutive uses. Also, make sure you mix well the oil & felt mixture just before doing a new electrode configuration demo. If the felt is let to settle, it will sit on the bottom of the glass dish and not move when electrifyiing the system.

We have a second setup that can be used in case two classes need this demo simultaneously (last image below). There is the choice of a new Glassman HV supply or one of two NAVPERS 70126 HV supplies.


  • Overhead Projector
  • Alligator Clips
  • Connecting Wires
  • Large Flat-Bottomed Bowl
  • Oil
  • Electrodes with Clamps
  • shredded felt
  • 10kV Power Supply