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Homework Help: Finding force on dipole

  1. Feb 23, 2006 #1
    I've worked this problem out, but I seem to get zero force on the second dipole due to the first dipole.

    The problem is situated as such:

    There are Q charges along the y axis: Q+ and Q-. They are a distance r apart. Their distance from the origin (at the center of the two charges) is r/2. This is the first dipole.

    The second dipole is on the the x-axis, to the right. These have charges q+ and q-. The distance q+ has from the origin is x-d/2, for q-, the distance is x+d/2. (q+ and q- are a distance 'd' apart).


    I took the force on each q+ and q- charge by Q+ and Q-. I took the tangent as the distance between them, but I seem to get zero.

    Also, how would torque on one dipole due to another be calculuated?
  2. jcsd
  3. Feb 24, 2006 #2


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    Homework Helper

    The force is a vector quantity hence we have to add them vectorically and then the resultant will not be zero on each charge q. The distances of +q and -q are different so the resultant force on +q and -q will not be zero.
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