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Homework Help: Electric Potential (I think I'm close?)

  1. Jul 23, 2008 #1
    1. The problem statement, all variables and given/known data
    A -3.2 { nC} charge is on the x-axis at x_1 = -9 {cm} and a 14.6 {nC} charge is on the x-axis at x_2 = 16 {cm}.

    ***At what point or points on the y-axis is the electric potential zero?

    2. Relevant equations
    (1/4*pi*epsilon_0)*[(q1/r2) + (q2/r2)] = 0V

    3. The attempt at a solution

    The way I've tried solving it is by setting (q1/r2) = (q2/r2)
    So 3.2*sqrt((16 cm)^2 + y^2) = 14.6*sqrt((-9 cm)^2 + y^2)
    Eventually getting -14644.52 = 202.92 y^2
    And y = +/- 8.5

    Unfortunately this answer isn't being marked as correct. Does anyone see something wrong with the way I'm trying to solve this?
  2. jcsd
  3. Jul 23, 2008 #2
    What happens when you square -9?

    Hint: [tex](y-y_0)^2[/tex]
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