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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
  video  - Back EMF in an Inductor
  video  - LR Circuit w/ Function Generator
 LR Circuit w/ Battery
  video  - Ringing LC Circuit w/ Function Generator
 Ringing LC Circuit w/ Battery
 Complex Circuits
 Semiconductors And Tubes
 Transmission Lines and Antennas

 video  - LR Circuit w/ Function Generator


Demonstrate the time constant of an LR circuit and its dependence on inductance and resistance.


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  DEMO VIDEO DOWNLOAD w/ sound / 854x480 / 5.69Mb/s / 105MB size  

Connect R and L in series and use the PASCO generator's square waves as a signal source. One can use a 110Ω resistor (or 10Ω or light bulb) and 4.25mH air core coil. Vary the values of L by sliding the iron rod through the inductor. Note that a brass, copper or aluminum rod does not affect L. Voltage across the resistor demonstrates the current dependence in the circuit. A schematic of the set up is shown in the last image below.


New Tektronix DPO 3014 Scope Setup:
  • There are two Instek GDP-025 differential probes attached to CH1 and CH2.
  • Scope has VGA output whose signal can be projected onto screen.
Old HP 1200A Scope Setup:
  • Use differential input oscilloscope to display both the charge and the current dependence.
  • A camera pointing at the scope's screen is available for the use in any of the rooms.


  • Large Bread Board
  • Inductor
  • Connecting Wires
  • Oscilloscope
  • Resistor
  • Wave Generator