PhysicsChapter 6: Electrostatics
Faraday Cage Idea
Introduction
A Faraday cage is a conducting enclosure that shields its interior from many external electric-field effects.
Definition
Principle
When an external electric field is applied, free charges in the conductor redistribute. This redistribution creates an opposing electric field inside the conducting material and, under electrostatic equilibrium, the electric field inside the enclosed conductor region is approximately zero.
Examples
* metal car body during lightning; * shielding around sensitive electronic equipment; * screened cables; * metal enclosures.
Car Example
During lightning, current tends to travel around the conducting exterior of a metal vehicle rather than through the passenger space. The protection comes mainly from the conducting shell, not from rubber tyres.
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Sticky Notes · Quick Revision
CONDUCTING SHELL
CHARGE REDISTRIBUTES
INSIDE FIELD
- ≈ zero electrostatically