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Homework Help: Electric field at origin, zero or nonzero?

  1. Aug 18, 2011 #1
    1. The problem statement, all variables and given/known data

    Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?

    2. Relevant equations

    3. The attempt at a solution

    If they were like charges, both positive, then I would say the electric field would be 0. I'm not sure because they are opposite polarities. Please help.
  2. jcsd
  3. Aug 18, 2011 #2
    Try to think of the electric field lines; if you drew them what would they look like?
  4. Aug 18, 2011 #3
    What would happen if I were to place a charge of -q at the origin?
    How about +q? Would you agree that they would move? What does
    this say?
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