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Homework Help: Parallel Conducting plates problem

  1. Jan 29, 2013 #1
    If we have two parallel conducting plates ( of surfaces 1msq each), set at a very small distance apart, so that the plates can be considered like infinite plates (no edge effect).

    Both plates are neutral at first.

    Now a charge (say +Q) is placed on one of the plates. the other still is neutral

    What will be the charge on each face of both the plates, and the field at A, B and C, where A is outer side of plate 1, B is middle of plate 1 and 2, and C in outer side of plate 2?

    My thoughts:
    i know that if the other plate also had an opposite excess charge then on the outer sides charges are 0 , while inside they would be +Q and -Q. so field would also only exist in the middle.

    but im a but confused on what it should be incase of only one plate with the excess charge?
  2. jcsd
  3. Jan 29, 2013 #2


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    Create unknowns for the four surface charges. You can immediately write down two equations based on knowing the total charge in each plate. Since there is no field inside either plate, you can develop two more equations.
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