How Faraday Cage Works & Its Applications


We all are surrounded by electromagnetic radiation. The unwanted signals produced by electronic devices often create disturbance and that’s where Faraday cages come in. Michael Faraday, the great 19th-century scientist, studied the work of earlier scientists such as Benjamin Franklin and invented Faraday Cage. So, what is a Faraday cage and how it works?

A Faraday cage is a metallic enclosure that prevents the entry or escape of an electromagnetic field (EM field). It is a conductive cage which is also known by other names like Faraday shields, RF cages, or EMF cages. This cage is designed to protect the inside from external electric fields and external electromagnetic radiation. It cancels out electric charges or radiation within the cage’s interior. Now you may ask how it works.

How to Build a Faraday Cage: Homemade DIY Project

During his research, Michael Faraday discovered that electromagnetic waves naturally flow around the surface of conductive materials, not through them. For instance, if a car is struck by lightning during a thunderstorm, the metal frame of the car acts as a faraday cage and draws the electricity away from the passengers inside. During his experiment, he wrapped a room in metal foil, placed an electroscope inside the room to measure electric charges, and then applied electrical charges to the outside of the room.

To build a Faraday cage, a conductive material is required. The conductive materials like metals allow electricity passes through them. The purpose of using conductive material is to protect what’s inside the cage from electricity. It is also lined with a non-conductive layer, so the cage has a conductive layer on the outside and a non-conductive layer on the inside.

Uses of Faraday Cage

The Faraday cage has become quite popular and is in use in our everyday lives. It is used in places and applications where stray EM fields must be kept out. A heavy-duty Faraday cage can protect anything inside against direct electrical charges.

From esoteric lab settings to common products, Faraday cages are used for a variety of purposes. The most common example of a Faraday cage is microwave ovens that reverse the effect and trap waves within a cage for cooking. Likewise, many other electronics also use Faraday cages to block out radio frequencies and electromagnetic noise disturbances that could impair their proper functioning. Power utility linemen who work on high-voltage power lines also wear specially made suits to reduce the risk of electrocution. You fly safely in airplanes through storm clouds because the plane’s cockpits and compartments are protected by metallic materials that act as Faraday shields. Moreover, MRI (magnetic resonance scanning) rooms in hospitals are also shielded to prevent stray electromagnetic fields from affecting a patient’s diagnostic images. The concept of Faraday cage also protects vital telecommunications equipment from lightning strikes and other electromagnetic interference. It is also used to design a shielded room that can block out eavesdropping technologies so that sensitive matters can be discussed.