Al Tobias (wat4y) - Office: Rm. 201, (434) 924-0538 - Lab: Rm. 202, (434) 924-6800
Demonstrations are cataloged according to PIRA Bibliography
PLEASE REQUEST DEMOS WELL IN ADVANCE
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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You have selected the following Demos:
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Lecher LinesPurpose:To demonstrate a standing electromagnetic wave.Procedure: Using our vacuum tube based CENCO 83 MHz RF oscillator, a standing radio wave (λ = 3.6m) is set up in two parallel copper wires 5.5 m long and 2.5 cm apart. To measure magnetic field intensity, a tuned RLC circuit apparatus, with filament bulb in it, is used to sense magnetic field produced by changing current in the transmission line. To measure E-field, a fluorescent tube is used to sense voltage difference between the parallel wires. Moving the probes along the lines, nodes and anti-nodes of the B and E fields can be found. CENCO Catalog describing a "Short Wave Demonstration Outfit". ie. In the open circuit case (the ends of the copper wires are unconnected), the end must be an E-field anti-node and B-field node). In the animation below, the top case is open circuit, the bottom case is closed circuit:black dots = current red arrows = voltage 
Hints:Caution: Don't touch the wires.Please, have the equipment ON only during the demonstration. Turn the oscillator OFF immediately after you finish with the demo.    |