What Happens When Current is Introduced into an Ungrounded Faraday Cage?

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Introducing current into an ungrounded Faraday cage does not create an electric field inside, as the charges redistribute to maintain equilibrium. If a charge is placed inside, the inner surface of the cage becomes charged, but this does not lead to a potential difference that would allow current to flow. In the event of a lightning strike, the cage protects those inside by redirecting the electric field around it, although a perfect cage is theoretically required for complete safety. Real-world cages may not be perfect, allowing for potential risks during extreme conditions. Thus, while a Faraday cage generally provides protection, it is not infallible against direct lightning strikes.
  • #31
Current will indeed flow through the wall of a Faraday cage; they have lights in there.

A car is not a particularly good Faraday cage. It is made of a poor conductor and has large openings together with lots of "sneak" paths.

There are at least two documented cases of a person(the same person!) being struck by lightning while inside a car (well, actually a truck in one case).
 
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  • #32
(From an earlier post of mine.) Member NoTime has mentioned the same thing.

In the ideal case, the Faraday cage should be an unbroken hollow conducting shell. Then there cannot be any electrical field inside due to outside fields. In practice, it is made of fine mesh, and connected to the ground, that is earthed.

A heavy duty properly grounded cage will prevent lightning from passing through. But, theoretically, it's possible to imagine an exceptionally powerful bolt of lightning entering it, because it's a mesh, not an unbroken hollow shell.
 

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