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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
 Complex Circuits
 Parallel LCR Circuit or Tank Circuit
  video  - Series LCR Circuit, Resonance
 Coupled Electrical Oscillators
 Semiconductors And Tubes
 Transmission Lines and Antennas

 video  - Series LCR Circuit, Resonance


To show the phase response in an LCR circuit and behavior of current at resonance.


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  DEMO VIDEO DOWNLOAD / no audio / 1920x1080 / 24.19Mb/s / 708MB size  

  DEMO VIDEO DOWNLOAD / no audio / 854x480 / 5.69Mb/s / 167MB size  

Resonant Circuit: We have a Tektronix scopes that utilizes two differential probes to accomplish floating measurements on the voltage across the light bulb (cyan) and the voltage across the inductor (yellow).

Connect a #14 bulb (acts as resistor), 4.25mH air core inductor coil and 0.47μF capacitor in series as shown in the image below. Use the PASCO function generator sine wave 10Vpp as a signal source. Vary the frequency of the generator to observe the resonance at about 3.6KHz (the bulb will light bright). Vary any of the system parameters (R,C, or L as in RC and LR demos) to observe the change in the resonance frequency. By simultaneously measuring the voltage across the inductor and capacitor, one will observe that at resonance these voltages are the same and 90o out of phase. Also at frequencies above the resonance the circuit becomes inductive (the voltage drop across C goes to zero) and at lower frequencies the circuit becomes capacitance driven.


Use our two Instek GDP-025 differential probes on channel-1 (yellow) and channel-2 (cyan) to perform floating measurements w/ our Tektronix DPO3014 oscilloscope.

The scope channels are:
  • ===== Channel 1 (yellow): Inductor
  • ===== Channel 2 (cyan): Current (voltage drop across light bulb)
  • ===== Channel 3 (magenta): Function Generator AC source
  • ===== Channel 4 (lime): Capacitor


  • Oscilloscope
  • Large Bread Board
  • Inductor
  • Connecting Wires
  • Capacitor
  • Resistor