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Homework Help: Conservation of Charge

  1. May 21, 2009 #1
    1. The problem statement, all variables and given/known data

    In the figure 21-40, three identical conducting spheres form an equilateral triangle of side length d = 24.0 cm. The sphere radii are much smaller than d and the sphere charges are qA = -3.45 nC, qB = -3.91 nC, and qC = +6.09 nC. (a) What is the magnitude of the electrostatic force between spheres A and C? The following steps are taken: A and B are connected by a thin wire and then disconnected; B is grounded by the wire, and the wire is then removed; B and C are connected by the wire and then disconnected. What now are the magnitudes of the electrostatic force (b) between spheres A and C and (c) between spheres B and C?

    2. Relevant equations
    F = kq1q2/r^2

    3. The attempt at a solution

    I got 3.28 x 10^-6 N for part A... not sure what to do for B and C
  2. jcsd
  3. May 21, 2009 #2


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    Homework Helper

    Follow the subsequent steps. When A and B are connected what charge ends on each? Then B is rounded so the charge on B is now 0. Now B and C are connected and you end up with how much charge on B and C?

    Now it looks like you're back to calculating forces again.
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