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A Faraday cage is an enclosure made of conductive materials which is capable of blocking external electric fields. In other words, it is a hollow conductor capable of keeping the charge or radiation on the external surface of the cage. Faraday cages are used in a wide range of applications, including protection of electronic devices from electrostatic discharge and external radio frequency interference.
A Faraday cage is also known as a Faraday shield.
A Faraday cage has a cage-like appearance, with some making use of fine metal mesh and others using simple chain-link fences. All Faraday cages can handle electrostatic charges and certain categories of electromagnetic radiation, and distribute them around the exterior of the structure. A Faraday cage functions by distributing the electric charge or radiation around the exterior of the cage. This rearrangement of the charges leads to cancellation of radiation or charge within the interior of the cage. However, it cannot block slowly varying magnetic fields from reaching within the cage, such as Earth’s magnetic fields. One of the best examples of a Faraday cage is a magnetic resonance imaging (MRI) scan room. In this case, they prevent the external radio frequency signals from interfering with the data captured from the patient.
Faraday cages have a wide range of applications. They are used for enclosing devices that can produce radio frequency interference, so that radio waves emitted are prevented from interfering with nearby devices. Other usages include providing safety against lightning and acting as protective suits for linemen working on high-voltage power lines.