Faraday Cage

- May 07, 2018-

Faraday Cage is a cage made of metal or good conductor. It is named after the English physicist Michael Faraday, who is the founder of electromagnetism. Faraday Cage is a device used to demonstrate the principle of isoelectric potential, electrostatic shielding, and high-voltage electrification. It consists of a cage, a high-voltage power supply, a voltage display, and a control section. The cage is connected to the ground. The high-voltage power supply delivers 100,000 VDC high voltage to the discharge rod through a current limiting resistor. When the tip of the discharge rod is 10 cm from the cage body, the discharge spark occurs. According to the electrostatic balance condition of the grounding conductor, the cage is an alloster, the internal potential difference is zero, the electric field is zero, and the charge is distributed on the outer surface of the discharge rod.



A Faraday cage is a metal enclosure that prevents the EM field from entering or escaping. An ideal Faraday cage consists of an unbroken, perfect conductive layer. In practice, this ideal state cannot be achieved, but it can be achieved by using fine mesh copper sieves. For best performance, the Faraday cage should be grounded directly.


The demonstration of the Faraday cage illustrates the principle of live work for high voltage workers. The protective clothing for the high-voltage live operator is made of metal wire. When it contacts with the high-voltage wire, an equal potential is formed so that electricity does not pass the operator's body , which provides a good protection. For example, a car is a Faraday cage. Since the car shell is a large metal shell, an isomer is formed. When the driver is driving on thunderstorms, people in the car do not need to worry about being struck by lightning.

The demonstration of the Faraday cage also demonstrated that the Faraday cage grounded on the enclosure can effectively block electromagnetic interference from inside and outside the cage and thus provide electrostatic shielding. Using this principle, scientists and technicians ground many metal casings of precision instruments and equipment, effectively avoiding unnecessary electromagnetic interference and lightning attacks.