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Homework Help: Electric Potential in a triangle

  1. Feb 28, 2010 #1
    1. The problem statement, all variables and given/known data

    What is the electric potential at the point indicated with the dot in the figure?
    The dot is in the center of an equilateral triangle with sides of 3 cm. The top point is a +2 uC charge and the bottom points are both -1 uC charges.

    2. Relevant equations

    V= kq/r

    3. The attempt at a solution

    I used 1.299 cm the distance from the center point to the charges. I then plugged in the values for each point and added them up. I DID however use +1 for the -1 uC charges because they add to the electric potential right?
  2. jcsd
  3. Feb 28, 2010 #2


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    Homework Helper

    You must use -1 x 10^(-6) for the -1 μC charge. The potential from the negative charge tends to cancel the potential from the positive charge. If you imagine the + and - charges slowly moving toward each other, the potential will not change suddenly when the charges contact and cancel each other out.
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