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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
 Semiconductors And Tubes
 Transmission Lines and Antennas
 Power Loss in Transmission Lines
 Flash Light Radio
 Fiber Optics Coupled Audio Device
 Lecher Lines
  video  - Microwave Oven Experiments
  video  - Electromagnetic Radiation
 FM Radio
 Spark Gap Tesla Coil

 video  - Electromagnetic Radiation


To demonstrate radiation of electromagnetic waves.


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  DEMO VIDEO DOWNLOAD / no audio / 1920x1080 / 24.19Mb/s / 351MB size  

  DEMO VIDEO DOWNLOAD / no audio / 854x480 / 5.69Mb/s / 78MB size  

The UNILAB Electrical Oscillation Apparatus is used to generate electromagnetic radiation. The setup is wired as shown in this schematic and in the images below. It is mounted on a wood poll so it is above the bench away from metal objects. The unit switch should be set to VHF.

A single turn "inductance" is plugged directly into the unit connecting grid capacitor and the anode of the triode. The "inductance" and the stray capacitance of the unit are forming an Hartley oscillator circuit. +300V DC anode voltage is applied through a 1.5KΩ power resistor, using crocodile clip toward the grid end of the loop. 6.3V AC is applied to the filament. Produced oscillations are ~ 140 MHz.

The oscillator is loosely coupled (3-5cm) to a λ/2 resonant antenna, mounted on a insulating stand. A λ/2 dipole with light bulb is used to detect and also to demonstrate polarization of the electromagnetic radiation.


  • Apparatus works better with alligator clip with red banana cable hanging over the top of the oscillator unit.
  • Brown Power Resistor: Ohmite "Divideohm" 1500 ohms, 100 Watts, 0.258 amps