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Homework Help: An easy electrodynamics question, and yet

  1. Sep 11, 2006 #1
    My first homework assignment for griffiths is underway.
    Here is a problem I can't figure out.

    Q. Two identical conducting small spheres are placed with their centers
    0.350 meters apart. One is given a charge of 12.0 nC and the other
    is given a charge of 16.0 nC The spheres are connected by a
    conducting wire. Find the electric force between the two after
    equilibrium has occurred.

    A. I used Coulombs Law to arrive at .000014 N. This is incorrect. My reasoning was that the conducting wire would allow electrons to redistribute themselves giving the two spheres the same charge which is the average of the two initial charges. I must not understand the concept of equilibrium correctly. I would ask the instructor but the faculty at my institution is on strike presently!

    Any suggestions?
  2. jcsd
  3. Sep 11, 2006 #2
    Well, even given your assumption (which feels right to me), I don't get the same answer as you do - I'm different by some exponent of 10. Are you certain about your answer?

    Also, I think there should be 3 significant digits in your answer.
  4. Sep 11, 2006 #3
    You were right in that it was a problem with the number of significant digits used. The homework is submitted online and the site used is a bit touchy.
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