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Homework Help: Electric potential energy and point charges

  1. Sep 21, 2009 #1
    1. The problem statement, all variables and given/known data
    Two point charges , Qz= +5.00 nanoC and Q2= -3.00 nanoC, are separated by 35.00 cm.
    a) What is the potential energy of the pair? What is the significance of the algebraic sign?
    b) what is electrical potential at a point midway between the charges?
    (here i'm supposing i'd do it the same way as in question a but divide the distance in half?)
    c)how much work is required to bring a charge Q3=+2.00nanoC from very far away to the point midway between the charges

    2. Relevant equations

    Im guessing i have to use deltaV=delta PE/q= - Ed but im still not sure about how to proceed because i have coulombs and these equations work in volts.

    Also, when it says separated by 35.0 cm, would this equal my height in the potential energy formula?
  2. jcsd
  3. Sep 21, 2009 #2
    There's no height. You're confusing it with gravitational potential energy. Look for a formula for the electrical potential energy for a system of point charges.
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