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Electric field generated from dipoles

  1. Dec 22, 2005 #1
    I'm having a little difficulty understanding the electric field generated from electric dipoles. As far as I know electric fields are generated on positive charges and terminated on negative charges. Since a dipole is a positive charge and a negative charge seperated by a very small distance, why doenst they just simply cancel each other out?

  2. jcsd
  3. Dec 22, 2005 #2


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    If the positive and negative charge were point charges at exactly the same location then they would cancel out. However, if the separation between them is finite (but as small as you like) then the cancellation is not exact.

    Mathematically, it's like this:

    [itex]\frac {1}{x}[/itex] and [itex]- \frac {1}{x}[/itex] cancel exactly when added together (we ignore x = 0 for this discussion) but [itex]\frac {1}{x-\epsilon}[/itex] and [itex]-\frac {1}{x+\epsilon}[/itex] do not cancel.
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