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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
  video  - Resistance Model
  video  - Temperature Effects on the Resistance of Copper Wire
 Temperature Effects on Resistivity
  video  - Superconducting Wire
 Electromotive Force And Current
 DC Circuits
 Magnetic Materials
 Complex Circuits
 Semiconductors And Tubes
 Transmission Lines and Antennas

 video  - Superconducting Wire


Show the resistance of a superconductor vanishes below the critical temperature. Tc = 90K for YBCO.


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  DEMO VIDEO DOWNLOAD w/ sound / 1920x1080 / 24.19Mb/s / 231MB size  

  DEMO VIDEO DOWNLOAD w/ sound / 854x480 / 5.69Mb/s / 55MB size  

This demo utilizes a short length of high temperature superconducting (HTS) wire, which is actually shaped like a ribbon with Yttrium Barium Copper Oxide (YBCO) sandwiched between two layers of stainless steel. Tc = 90K. For example, STI describes some of the different superconducting wires.

Connect power supply to black and red leads. Connect the other two leads to the microvoltmeter.

Turn ON the power supply and adjust the current until 1/2 A flows through the wire. The room temperature voltage will measure just under 2mV.

Have students watch the reading on the voltmeter while the LN2 is poured into the Styrofoam container. After a few seconds, the voltage drop across the wire will fall to zero.


Must use a power supply that can control current:
  • Keithley 2231-30-3 Triple Channel DC Power Supply
  • HP 6214A DC Power Supply
Must use a voltmeter that can measure down to 1μV:
  • Keysight 34461A Digital Multimeter
  • Keithley 177 Microvoltmeter


  • Digital Multimeter
  • Superconducting wire apparatus