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Faraday Cage

Faraday Cage

Credit: Anna Hanks
Source: http://www.flickr.com/photos/annaustin/5506800480/
License: CC BY-NC 3.0

By standing in a conducting enclosure, this person is protected from the static electric discharge that would otherwise harm them.

News You Can Use

  • Faraday cages are built by taking a conducting material and forming an enclosure. This conductive enclosure is able to block external electric fields. This shielding effect is possible because when an external electric field hits the Faraday cage, the electric charges within the conducting material are distributed such that they cancel the effect of the field inside the cage. While Faraday cages are used to protect electronic equipment from external electrical discharges, they are unable to block static or slowly varying magnetic fields.
  • Credit: Alex Healing
    Source: http://www.flickr.com/photos/alexhealing/5816447240/
    License: CC BY-NC 3.0

    A Faraday Cage blocking an external electrical current [Figure2]

     

  • Watch the following video to see a demo of Faraday’s cage: http://www.youtube.com/watch?v=WqvImbn9GG4
  • Some examples of Faraday cages that are seen in everyday life are:
    • Elevators with a conducting frame
    • Microwave oven
    • The scan room that is a part of an MRI

Show What You Know

Using the information provided above, answer the following questions.

  1. If an airplane was not shielded from a lightning strike by a Faraday cage, what would happen to the electronics of the airplane?
  2. How could a Faraday cage be useful to prevent electronic eavesdropping?

Image Attributions

  1. [1]^ Credit: Anna Hanks; Source: http://www.flickr.com/photos/annaustin/5506800480/; License: CC BY-NC 3.0
  2. [2]^ Credit: Alex Healing; Source: http://www.flickr.com/photos/alexhealing/5816447240/; License: CC BY-NC 3.0

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