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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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 Quantum Effects
  video  - Photoelectric Effect in Zinc
 Stopping Potential
 Photoconductor (resistor)
  video  - Electron Diffraction
 Quantum Levitation (Flux Pinning)
 Atomic Physics
 Nuclear Physics

Photoconductor (resistor)


To demonstrate the operation of the photoconductor (photoresistor). Photoconductor is a poor semiconductor in which the conduction and the valence band are so closely spaced that a visible light source provides enough energy to the electrons to switch the bands thus reducing the sample resistance with brighter light.


Connect the photo resistor apparatus to a DC voltmeter. Apparatus is just a pot resistor connected in series with the photo resistor. By shining the light on the photo resistor the voltage drop across the pot increases.