High School Physics

Faraday Cage & lightning

Last updated on May 14th, 2022 at 01:21 pm

In this post, we will find out what a Faraday cage is and how this is related to lightning strikes.

What is a Faraday Cage?

A Faraday Cage, named after British physicist Michael Faraday, is a cage, metal grating, or metallic box that can shield electrical charge.

Charges gather on the outer shell of the cage because they are repelled by one another and can be further from each other if they are on the outside of the cage. This results in no charge within the Faraday Cage.

The metal sphere of a Van de Graaff generator is a Faraday Cage. Cars and airplanes can be Faraday Cages as well and may provide some protection from lightning during an electrical storm.

Why is a car often the best place to be when lightning strikes?

It is not because of the rubber tires!

The real reason why a car is a safe place to be when struck by lightning is that most cars have metal bodies, which act as Faraday Cages, keeping all the electrical charge on the outside of the car.

Since the charge is kept on the outside of the vehicle, the person sitting inside the car is kept perfectly neutral and safe. It is the shielding of the metal car body, and not the rubber tires, that protects people in automobiles.

What happens to an airplane when it is struck by lightning?

Airline pilots tend to avoid thunderstorms, but when a plane is struck by lightning, the passengers inside the plane are kept perfectly safe, for they are inside a Faraday Cage, which shields them from the massive electrical charge.

The lightning can, however, disturb and even destroy some of the sensitive electronics used to fly the plane.

Studies were performed by NASA in the 1980s in which they flew fighter planes into thunderstorms to see how the planes would react to lightning. The scientists quickly found that the planes actually encouraged lighting, because the planes caused increases in the electric field of the cloud, which in turn caused the lightning to hit the plane’s metal body.

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