In electromagnetism, the
Faraday cage or shield is an application of Gauss's law, one of Maxwell's equations. Gauss's law describes the distribution of electrical charge on a conducting form, such as a sphere, a plane, a torus, etc. Intuitively, since like charges repel each other, charge will "migrate" to the surface of the conducting form, as described below. The application is named after physicist Michael Faraday, who built the first
Faraday cage in 1836, to demonstrate his finding. A Faraday shield is used generally for any kind of electrostatic
shielding.
In
MRI, one use of the Faraday shield is the
shielding of the scanning room, to block incoming
radio frequency (RF) signals which would contaminate the send and received signals of the
MRI scanner, and it suppresses RF signals, which would else pollute the environment around.