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Homework Help: Show that the potential at a generic point for x positive is zero

  1. Jul 24, 2011 #1
    1. The problem statement, all variables and given/known data

    Show that in this set-up, the potential at a generic point (-x, 0, 0) (for x positive) is zero:

    two point charges placed at (-a, 0, +a) and (-a, 0, -a)
    the mirror charges are (a, 0, +a) and (a, 0, -a)

    3. The attempt at a solution

    V=(q/(4 pi epsilon0)) ((1/(sqrt((x^2 -a^2)+a^2))+(1/(sqrt((x^2 -a^2)+a^2)))

    this does not equal zero

    by the way, please DO NOT DELETE THIS POST, MODS, I ASSURE YOU I HAVE NOT POSTED THE SAME QUESTION. IT IS A TOTALLY DIFFERENT PART OF A QUESTION I POSTED EARLIER.
     
  2. jcsd
  3. Jul 24, 2011 #2
    Yeah, you're right, the voltage is not zero. That's weird. Are you sure the charges are supposed to be the same? Opposite charges at those locations would give V = 0.
     
  4. Jul 24, 2011 #3
    thanks, sorry, i wasn't paying attention to the part of the question that said 'two point charges +q and -q'
     
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