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Homework Help: Electric Potential/Work - POint Charges on a Square

  1. Feb 12, 2009 #1
    1. The problem statement, all variables and given/known data
    two identical point charges are on diagonally opposite corners of a square that is 0.5m on a side. Each charge is +3 x 10^ -6 C. How much work is done by the electric force when 1 charge moves to an empty corner?

    2. Relevant equations

    W= u= qV = q(kq/r) = kq^2/ r (is this right??)

    3. The attempt at a solution

    w= kq^2 / r = (k)(+3 x 10^ -6)^2 / (.5)

    the real answer is -4.7 x 10^-2 but i dont know how to get that. thanks
  2. jcsd
  3. Feb 12, 2009 #2


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    Homework Helper

    Almost! It is the "W = u" part where you err. This U is the potential energy. The work done is the difference between the U at the beginning point and the U at the ending point.
    You already have it half done.
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