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Homework Help: Electric dipole in electric field.

  1. Nov 14, 2008 #1
    1. The problem statement, all variables and given/known data

    An electric dipole moment, vector P, is initially pointing in the directio of a uniform electric field, vector E (say, in the positive x direction). How much external work is needed to turn the dipole by 90 degrees?

    2. Relevant equations

    vector P is directly proportional to E. It will tend to point in the same direction as E.

    3. The attempt at a solution

    The only relevant equation I can gather is the torque N = p X E.
  2. jcsd
  3. Nov 14, 2008 #2
    What's the energy of a dipole in an electric field? That equation should be right next to the equation you mention!
  4. Nov 15, 2008 #3
    E of a dipole in an electric field = k * P/r^3

    Wouldn't I need a force, as in F*d to find work?
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