5N10.60 - Electromagnetic Radiation - Radio Transmitter
See also 5N10.60 in Optics.
Connect the power supply to the transmitter and attach the antenna. Insert the antenna into the bulb receiver unit. Turn on the transmitter and bring the receiver close to the transmitter so that the antenna of both units are parallel. As the light bulb comes on, tune the receiver antenna to maximum reception. If the transmitter is set between two parallel walls the unit will set up standing waves that can be detected with the receiver. The most nodes that I have ever detected is 6 in LR I going from the lecture bench to the back of the room.
This demo will also show polarization characteristics. Find a node that lights the bulb brightly. Turn the receiver antenna from parallel to perpendicular and the light will go out. Turn back to parallel and it will come back on.
This unit does interfere with and can do damage to the lecture room microphones so be sure that they are turned off when you operate the demo. Also, only operate the unit when demonstrating as there is the possibility of interruption of other radio transmission within a block of the transmitter.
One variation of this is to replace the small light bulb and antenna receiver with a 6" fluorescent tube. When brought close to the middle or ends of the transmitting antennas the tube will light up brightly.
You may also pick up the transmitter transmission with the Radio Shack battery powered radio that has been tuned to 99 to 100 MHz.
- Thomas B. Greenslade Jr., "The Central Scientific Company and Its Apparatus", TPT, Vol. 59, #2, Feb. 2021, p. 94.
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- Todd Peterson, "HAARP, The Most Powerful Ionosphere Heater on Earth", Physics Today, Vol. 68, #12, Dec. 2015, p. 72.
- Paul E. Klopstfg, "An Apparatus For Demonstrating The Fundamentals of Radio", Reprint School Science and Mathematics, Vol. XXIX, #5, May 1929.
- Brett Carroll, "Demo Memos", PIRA Newsletter, Vol. 1, #1, Oct. 1985, p. 3.
- G. D. Freier and F. J. Anderson, "Ep-13", A Demonstration Handbook for Physics.
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- "Directions for Operation of Cat. No. 80435 Short Wave Radio Demonstration Apparatus", Central Scientific Company.
- "Directions for Operating Cat. No. 80453 Standing Wave Apparatus", Central Scientific Company.
- "High Frequency and Radio Demonstration Apparatus", CENCO Catalog, 1930, p. 1325.
- Grant Mellor, "29. The Birth of Radio", Flying Tinsel, 1993, p. 127 - 129.
- W. Bolton, "48. The Half-Wave Dipole", Book 4 - Electricity, Physics Experiments and Projects, 1968, p. 93 - 94.
- W. Bolton, "47. Very High Frequency Standing Waves", Book 4 - Electricity, Physics Experiments and Projects, 1968, p. 91 - 92.
- W. Bolton, "46. Very High Frequency Oscillations", Book 4 - Electricity, Physics Experiments and Projects, 1968, p. 89 - 90.
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