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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
 Current and Resistance
 Electromotive Force And Current
 DC Circuits
 Magnetic Materials
 Complex Circuits
 Parallel LCR Circuit or Tank Circuit
  video  - Series LCR Circuit, Resonance
 Coupled Electrical Oscillators
 Semiconductors And Tubes
 Transmission Lines and Antennas

Parallel LCR Circuit or Tank Circuit


To demonstrate inductive and capacitive reactance, resonance, and response of an LC tank circuit.


Use the R or C switch position on the substitution box and connect the circuit. Connect the scope to the points indicated and ground it to the function generator. The generator acts like a current source to drive the tank circuit so at resonance the current (Ch. A) will be in phase with the voltage across the tank circuit (Ch. B). Slightly below resonance, the tank circuit behaves inductively and the voltage will lead the current. Slightly above resonance, the circuit behaves capacitively and the voltage will lag the current. Also, at resonance, since the impedance of the tank circuit is infinite (ideally, assuming no losses, etc.), maximum signal voltage will be seen. The Q for this circuit is fairly good so a nice peak around resonance can be seen. Resonance for the above circuit occurs at about 7.8 kHz. A schematic for the setup is shown below.


Use 4.5 mH copper coil inductor


  • Oscilloscope
  • HP sine wave generator
  • Resistor - Capacitor Substitution Box
  • Inductor