PURPOSE: To show the shielding effect of Faraday Cage.
DESCRIPTION: A small radio is turned on and plays music from a local radio station. Place the Faraday cage over the radio. What happens?
When the Faraday cage is lowered over the radio, the cage stops the radio waves and the music cannot be heard. How does this amazing contraption work? The Faraday cage is made of a mesh of some conducting material. When a charge (provided by the radio) is placed inside an ungrounded Faraday cage, the internal face of the cage becomes charged, causing the redistribution of charges in the cage's body, preventing the existence of a electric field in the body of the cage. This causes the outer face to become charged equally in sign and magnitude to the one placed inside the cage. As the internal charge and the inner face cancel each other out, the spread of charges on the outer face is not affected by the position of the internal charge inside the cage. Therefore, the cage will generate the same electric field it would generate if it was simply charged by the charge placed inside.
EQUIPMENT: Radio and Faraday cage
SETUP TIME: None.
REFERENCES: Zhu E-qing, Electromagnetic Shielding, TPT 27, 686 (1989)
Faraday cage. (2007, June 11). In Wikipedia, The Free Encyclopedia. Retrieved 14:41, June 14, 2007, from http://en.wikipedia.org/w/index.php?title=Faraday_cage&oldid=137447102
Note: From 1995 to 2007 this demo was incorrectly listed as 5B15.35