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Voltage between two different charges

  1. Nov 22, 2009 #1
    Voltage = Charge / Capacitance.

    This assumes that the capacitor has +Q charge on one side and -Q charge on the other side.

    What if you have two different charges?

    I mean in terms of static electricity, if you have a piece of metal with one charge, and another piece of metal with another charge, the capacitance between them depends on their distance from each other and their volume... But they have two different charges.

    How do you find the voltage?

    Thank you,
    Last edited: Nov 22, 2009
  2. jcsd
  3. Nov 22, 2009 #2


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    I think by using the formula [tex]V=-\int \vec E d \vec l[/tex] so you'd have to calculate the electric field of the charged capacitor.
  4. Nov 22, 2009 #3
    Indeed, after spending a while on http://en.wikipedia.org/wiki/Capacitor#Parallel_plate_model", I found that E = +- charge density / some constant ..
    It goes on taking the integral of E * something = Voltage

    But, I don't understand what E equals if you have two different charge densities.

    Does anybody?

    Note that it seems safe to assume that charge is proportional charge density, so we are still trying to figure out the original problem:
    What voltage do you get based on two different charges?
    Last edited by a moderator: Apr 24, 2017
  5. Nov 22, 2009 #4


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    You'd have to find out [tex]\vec E[/tex], I believe but not 100% sure. This value may depends on the type of capacitor and its shape.
    I'll wait someone else to enlighten us.
    Last edited by a moderator: Apr 24, 2017
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