5B20.35-Faraday Cage

Video: Watch this demo

Instructor’s video

Description: The radio will loose reception in the cage because electromagnetic radiation (which includes radio waves) will not penetrate the cage. Conductors prevent electric fields from existing within them.


  • Fine mesh Faraday Cage
  • Radio

Setup Procedure:

  1. Tune the radio to an AM station.
  2. Test to make sure the radio looses the signal when put inside the Faraday cage.

Demonstration Procedure:

  1. Turn the radio on and note that it picks up the AM radio station.
  2. Place the radio inside the Faraday cage and put the cover on top.
  3. Note that the radio looses the signal since E&M waves don’t enter the cage.

Note: Works best with an AM station. Also, the finer the wire mesh, the better it blocks the radio waves.

Concept: This demo is frequently used to illustrate that the electric field in a cavity enclosed by a conductor is zero everywhere inside the cavity. Because charges are free to move within a conductor, they will arrange themselves in such a way that they will cancel the electric field within the conductor. This is because if the electric field were not zero, charges within the conductor would move in the direction of the electric field. Since radio waves are a form of electromagnetic radiation, the faraday cage will block them from entering the cage in order to prevent any electic field within the cage.