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Electrostatics of conductors

  1. Feb 25, 2009 #1
    "In a static situation, the electric field of a conductor can have
    no component parallel to the surface coz this would violate the condition
    that the charges on the surface are at rest." would this statement be valid
    for electric field at the surface of an insulator? Explain your answer and
    the reason for any differences b/w the cases of a conductor and an

    So, first I thought that this statement won't be valid coz charges can't
    move in an insulator but then I thought that these charges could be excess
    charges and not mobile charge carriers. So, the statement should be valid.
  2. jcsd
  3. Feb 25, 2009 #2


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    Homework Helper

    Kind of a tricky question. The first sentence is incomplete. On a conductor, the charges are free to move and if there was an E along the surface it would cause the charges to move such that that E would be cancelled out. In most cases this would be a uniform distribution of charge whose combined E at any point would be perpendicular to the surface.

    On an insulator, the charges can't move. You could put a spot of charge in one place only and the resulting E would go out in all directions from that spot.
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