5B20.30 - Faraday's Cage - Electroscope

Code Number:
5B20.30
Demo Title:
Faraday's Cage - Electroscope
Condition:
Good
Principle:
Electrostatics
Area of Study:
Electricity & Magnetism
Equipment:
Faraday's Cage and Braun Electroscope.
Procedure:

Put the electroscope  inside the Faraday's cage. No charging of the electroscope should be observed when the Van de Graaff is turned on.

You may also use a flexible mesh screen for a simpler form of this demonstration. Stretch the screen between two poles and place aluminum "leaves" on both sides of the screen. Charge the screen, the "leaves" will deflect away from the screen, and then bring the two ends together forming a cylinder. The "leaves" on the inside of the cage should go down while the ones on the outside go up or out. Retry the experiment but twist one end so you make a Möbius strip and observe the "leaves".

References:
  • Joon Hee Hong and Jung Bog Kim, "Demonstration of a Faraday Cage Using a Metal Leaf Electroscope", TPT, Vol. 57, #5, May 2019, p. 334.
  • Seán Stewart, "Flexible Faraday Cage with a Twist: Surface Charge on a Möbius Strip", TPT, Vol. 45, #5, May 2007, p. 268.
  • Paul Gluck, "The Flexible Faraday Cage", TPT, Vol. 42, #3, Mar. 2004, p. 181.
  • Jim Hicks and Chris Chiaverina, "The Authors Reply", TPT, Vol. 23, #2, Feb. 1985, p. 126.
  • R. Dollinger, W. J. Sarjeant, J. R. Laghari, D. Dettman, M. Nikolich, John Shea, Marianne Rickley, and Michael Belling, "But is it Safe?", TPT, Vol. 23, #2, Feb. 1985, p. 70, 126.
  • Mario Iona, "Not Really Shocking", TPT, Vol. 23, #2, Feb. 1985, p. 70.
  • Chris Chiaverina, "A Faraday Ice Pail Convincer", TPT, Vol. 22, #8, Nov. 1984, p. 531.
  • Freier and Anderson, "Ea-20", A Demonstration Handbook for Physics.
  • Julien Clinton Sprott, "4.7, Faraday Cage", Physics Demonstrations, ISBN 0-299-21580-6, p. 197.
  • 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.
  • Brian Jones and Matt Fackelman, "Radio Shack - Stopping Electromagnetic Waves", Don't Forget the Duct Tape - a Little Shop of Physics Publication, p. 97.
  • Rudolf F. Graf, "Shielding Your Electroscope", Safe and Simple Electrical Experiments, p. 18.
  • Borislaw Bilash II, “Faraday's Cage“, A Demo A Day – A Year of Physical Science Demonstrations, p. 280.
  • Julius Sumner Miller, Q221 & A221, Millergrams II – Some More Enchanting Questions for Enquiring Minds, p. 68 & 116.






Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.