Understanding The Faraday Cage

By Author: Rob Thomas
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The Gauss's Law states that the total of the electric flux out of a closed surface is equal to the charge enclosed divided by the permittivity. So, in layman's terms, it means the total unit charge in a closed system is the same or constant. The charge in an segregated system is the same. So, as a consequence of this Law, Michael Faraday conceptualized the Faraday Cage. This cage is a covering or insulator that keeps the interiors safe from electromagnetic waves and strong electric fields. In continuation with Gauss's theory, all the extra energy or charge, positive or negative in a conductor must be retained on the surface of the conductor, if it is an equilibrium state.

The Faraday Cage was built in 1836, was and is based on these principles. It is a closed electricity conducting cell. It is usually made of a shell made of wire mesh or a solid conducting shell. It's chief purpose is to keep a region totally cordoned off. The shell never has electric field inside, inspite of being placed in extremely strong external fields since the charges on the conducting surface rearrange themselves till the time the electric charges ...
... inside are at zero.

The cage is unable to block static and the magnetic fields that change slowly, for instance, the Earth's magnetic field. Most probably, they (magnetic fields) cover or provide insulation to the interior from the exterior which may have electromagnetic radiation. The operation mostly dpends on the fact that an external electrical field (static) will cause the electrical flux (charges) within the cage's conducting material to redistribute themselves which helps to cancel the field's effect in the cage's interior. In this method, electronic equipment from lightning strikes and other electrostatic charges.

Operation:

To work properly a Faraday Cage must have important physical attributes. The most important thing is, it is a solid shell that is made of a material that helps in the conduction of electricity. The most important principle involved in its working is, it has to completely cover its interior region. Due to its outer shell, the cage cannot have electrical fields, neither outside nor inside. In case it approaches a highly electrical zone, the charges on the shell rearrange themselves till they can nullify electrical activity inside. It works both ways. If the intrior of the cage has an electrical field, the charges remain inside and there is no escape.

Uses:

1)Lightning insulation- The basic reason why people do not get struck by the lightning when travelling by a car and a plain is mainly due to the Faraday effect. The enclosure acts as a cage and keep the electrical charges away from the interior. However, in times like these, one must touch the metal body as that can lead to instant death.
2)Industrial- It is also used to keep the electromagnetic fields safe from external interruption. Usually rooms in an industrial outlet, such as a computer server room may be built as a cage
3)Blocks electromagnetic waves- They are an used in certain construction sites. It can act as a protective covering from an electric field.
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