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Homework Help: Electric field halfway between dipole isn't 0?

  1. May 18, 2010 #1
    I was just wondering... say you have a dipole, and you wanted to find the net electric field right in the middle.

    The electric field from the electron will be:
    E = k(-1.60*10^-19)/r^2

    The electric field from the proton will be the same magnitude, but opposite direction. Therefore, the net electric field should be zero right?
  2. jcsd
  3. May 18, 2010 #2
    Say the dipole is located at the origin and oriented along they y axis. If the electron is at x=-a and the proton at x=a then they both contribute equally to the magnitude of E at the origin as you said, but think about the direction in which the E vector at the origin points due to each particle again. For a positive charge E points away and for a negative charge E points towards right?
  4. May 18, 2010 #3
    ohhh - so since they are both in the same direction... they add to a non-zero number...?
  5. May 18, 2010 #4
    Correct. They both point in the same direction, that is, in the direction from the proton to electron. So the field there is nonzero.
  6. May 19, 2010 #5
    It's very large in between the charges.
    If the charges were the same polarity there would be zero field at a point but this isn't a dipole.
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