Electricity & Megnetism

lectrostatic shielding

Electrostatic shielding occurs when excess charges on a conductor are evenly distributed on its surface and the electric field inside is zero.

Electronic devices, such as DVD’s, are encased in a metallic cover to avoid being damaged by an external electric field.
When an electrically conducting body is electrified by one of the electrification processes, the electric charges are uniformly distributed on its surface. This happens because electric charges tend to move away, according to the principle of repulsion between charges of the same sign, until they reach a rest condition, electrostatic equilibrium .

One of the properties of a conductor in electrostatic equilibrium is that the electric field inside it is null precisely because of its charge distribution. This phenomenon is known as electrostatic shielding .

Electrostatic shielding was proven in 1936 by Michael Faraday (1821-1867) through an experiment that became known as the Faraday cage . In this experiment, this scholar entered a cage and sat on a chair made of insulating material. Then this cage was connected to a source of electricity and subjected to an electrical discharge, but nothing happened to him. With this, Faraday was able to prove that a body inside a conductor is isolated and does not receive electrical discharges due to the distribution of charges on the surface.

Metal clothing prevents the person in the figure from receiving an electrical shock

This phenomenon is widely used to protect equipment that cannot be subjected to external electrical influences, such as electronic devices. If these appliances are subjected to an external electric field, their components may be damaged. Furthermore, it is also thanks to the electrostatic shielding that, if a car or plane is struck by lightning, the people inside will not suffer any damage, as the metallic structure provides the electrostatic shielding of its interior.

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