|
|
Code Number: 5B20.35
Demo Title: Faraday's Cage - Radio
Condition: Good
Principle: Electrostatics
Area of Study: Electricity & Magnetism
Equipment:
Cell Phone and Aluminum Foil, Faraday's Cage, and Transistor Radio.
Procedure:
Cell phones are miniture radio transmitters/receivers. Have someone call your cell phone in class and see that the phone will ring. Wrap the phone in aluminum foil and repeat the experiment. The phone does not receive the signal and therefore does not ring. NOTE: If the aluminum foil touches the phone it will act like an antenna extension and receive the call. Put the phone into a plastic or insulated bag before wrapping with aluminum foil.
Put the radio in the Faraday's cage. When the radio is placed inside the Faraday's cage it will be unable to receive radio signals.
NOTE: Grounding the base of the cage may help improve the radio demo.
References:
- Zhu E-qing, "Electromagnetic Shielding", TPT, Vol. 27, #9, Dec. 1989, p. 686.
- Edward J. Carlone and Hugh D. Young, "Radio and TV Reception", TPT, Vol. 22, #3, Mar. 1984, p. 180.
- Borislaw Bilash II and David Maiullo, "Keep It Out of the Cage", A Demo a Day: A Year of Physics Demonstrations, p. 248.
- Jearl Walker, "5.3. Lightning: Vehicles", The Flying Circus of Physics Ed. 2, p. 220.
- Robert Ehrlich, "O.6. Shielding a Radio", Turning the World Inside Out and 174 Other Simple Physics Demonstrations, p. 174 - 175.
- Brian Jones and Matt Fackelman, "Radio Shack - Stopping Electromagnetic Waves", Don't Forget the Duct Tape! - The How and Why of the Experiments of the Little Shop of Physics - A Work in Progress, p. 97.