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Al Tobias (wat4y) - Office: Rm. 201, (434) 924-0538 - Lab: Rm. 202, (434) 924-6800

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  - Parallel Plate Capacitor
  video  - Simple Properties of Dielectrics
  video  - Capacitor Discharge
 Current and Resistance
 Electromotive Force And Current
 DC Circuits
 Magnetic Materials
 Complex Circuits
 Semiconductors And Tubes
 Transmission Lines and Antennas

 video  - Simple Properties of Dielectrics


To demonstrate that an electric charge while deposited on the surface of a dielectric stays on the surface of the dielectric.


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  DEMO VIDEO DOWNLOAD w/ sound / 1920x1080 / 24.19Mb/s / 260MB size  

  DEMO VIDEO DOWNLOAD w/ sound / 854x480 / 5.69Mb/s / 64MB size  

Setup the inductive spark gap apparatus connected to a 12V car battery (or preferably a DC Power Supply) as shown in the picture: attach a metal plate to one terminal and a sharp pointer to another. Place a dielectric crystal on the metal plate underneath the pointer so that the pointer is just above the crystal surface. Turn the apparatus on and observe the charge float on the surface of the dielectric towards the conductor. The induction coil apparatus causes sparks at a frequency of roughly 1Hz. The multiple lightning strokes to the conductor can be clearly seen.


Switch the voltage polarity to see the difference between positive and negative lightning.


  • Dielectric Crystal
  • Spark Generator
  • 12 V Car Battery
  • DC Regulated Power Supply