Uses of a Faraday Cage: Protection from Lightning and Computer Security

The Faraday cage acts as a shield, both to protect the inside and outside from strong electric fields or electromagnetic wave. The principles have been around for a long time, with the cage getting its name from Michael Faraday, who discovered its effects in 1836. Today, Faraday cages are used for many purposes, from protecting airline passengers from lightning strikes to preventing interference with computer network servers.

Uses of a Faraday cage: How it works

To work properly, a Faraday cage must have certain physical characteristics. The most important is that it is a solid shell that is constructed out of a material that conducts electricity. The Faraday cage does not have to be made from solid metal, as a mesh of wire will work just as effectively. The key principle is that it must completely surround its interior region. Because of its outer conductive shell, a Faraday cage cannot have an electric field both inside and out. When placed in the middle of a strong electric field, the charges on the conductive shell will rearrange until they nullify any electric activity on the inside. The same effect happens in reverse. If an electric field is placed inside a Faraday cage, the conductive shell will keep it trapped inside.

Uses of a Faraday cage: Blocks electromagnetic waves

Because the electrical current cannot travel through a Faraday cage, they have become very useful in certain construction and technological industries. A Faraday cage can be an effective shield to protect the rest of a building from a strong electric field. Electromagnetic waves can also be blocked by using a Faraday cage as long as the holes in the cage are narrower than the electromagnetic wave's wavelength.

Uses of a Faraday cage: Protection from lightning

One of the most common uses of Faraday cages is protection from lightning. The Faraday effect is the reason people do not get electrocuted when struck by lightning while riding in a metal airplane or automobile. The metal enclosure functions as a Faraday cage and keeps the electrical field away from the interior. Passengers should be careful not to touch any part of the metal body as the material will conduct electricity and they will be burned or injured.

Uses of a Faraday cage: Industrial uses

Faraday cages are also used to keep certain electrical or electromagnetic fields safe from external disruption. This can prevent interference with technological instruments that require precise calibration. For large industrial uses, such as computer server rooms, the entire room can be built as a Faraday cage. The only drawback in constructing an office building in this manner is that the metal shell of the Faraday cage may prevent cellphones and other wireless devices from functioning properly.