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Homework Help: Electric Field due to Capacitor Plates

  1. Mar 4, 2010 #1
    1. The problem statement, all variables and given/known data

    A capacitor consists of two plane parallel plates, separated by a distance d. The space in between is filled with a uniform charge density J. Find the electric field at a point x away from the positive plate when a potential difference V is applied.

    2. Relevant equations

    3. The attempt at a solution

    I am finding it difficult to locate this point in the setup -- as in, whether it is located outside to plates or inside. I am assuming that it is the latter. I know that the field produced by an infinite plate is (charge density)/2*epsilon_o, but none of my calculations give me something that matches the answer, which happens to be:

    V/d - J*(d-2x)/(2*epsilon_o)

    Any help would be great.
  2. jcsd
  3. Mar 4, 2010 #2
    There is a uniform charge distribution (which probably means the distribution is not a conductor) between the capacitor plates. Thus, the net electric field between the plates is E = E0 - Eind. E0 would be the electric field without the charge distribution in between (which probably correlates to the V/d in the expression) and Eind is the electric field induced by the charge distribution.
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