PHYSICS 7D Lecture Notes - Lecture 8: Faraday Cage, Equipotential, Electric Field
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Document Summary
The surface of a conductor is always an equipotential surface. The electric field just outside a conductor is always perpendicular to the surface. The entire solid volume of a conductor is at the same potential. We argued that the e field outside and parallel to the surface is zero since it is continuous. The charge in potential is path independent, so going from one point to the same point by any path, v=- e*ds=0. Through all the paths from a to b including paths inside the cavity, no work done. Free charge in conductor re-distribute to cancel external electric field. In space surrounded by conductor, e-field is always zero=> faraday cage is. All charge is on surface of conductor, but may not be uniformly distributed: electrical breakdown. At high electric field (~3*10 6 v/m), air is ionized and is conductive. Electric current bridges the air gap between two conductors.
