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Confused about the electric field at the surface of a conductor

  1. Apr 30, 2013 #1
    We know that the electric field at the surface of a conductor only have a normal component equal to ρ /ε (finite number).
    But let’s consider the point P (at the surface of a conductor ) . Assume that there is a charge at an infinitesimal distance from the point p . we can obtain the field at the P by the fourmula (E=Kq/r) .obviously, E ~1/r. so the normal component of the field is infinite. Now if we add the field due to other charges, it will remain infinite. So where could I be possibly wrong?
  2. jcsd
  3. Apr 30, 2013 #2

    Simon Bridge

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    It's the gradient of the electric field that has that value.

    The charges in the conductor will respond to the electric field of the small charge close to the conductor - affecting the way the total field comes out. How do they respond?

    Note - at a very small distance from a point charge, the field is not infinite.
    If the charge is actually at point P, then it is part of the conductor. Inside a conductor, the charges are infinitesimally small (in this model).
  4. Apr 30, 2013 #3
    You should ask yourself what exactly is "q" in that equation going to be for your capacitor with a given charge density (*cough*) ρ
  5. May 1, 2013 #4
    please note that the charge is <within> the conductor
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