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Homework Help: Electrostatic potential

  1. Dec 3, 2007 #1
    1. The problem statement, all variables and given/known data
    (Objective type question)
    Consider a square ABCD of side a, with charges +q, -q, +q, -q placed at the vertices, A, B, C, D in a clockwise manner. The electrostatic potential at some point located at distances r(r>>a) is proportional to?

    2. Relevant equations

    [tex]V =\frac{1}{4\pi \epsilon_0}\sum_i \frac{q_i}{R_i}[/tex]

    3. The attempt at a solution

    From the equation for the electrostatic potential is the obvious that V will be proportional to 1/r. I am a little confused by the options given to me...so just want to confirm.

    Other options:
    a] Constant
    b] 1/r^2
    c] 1/r^3
  2. jcsd
  3. Dec 3, 2007 #2
    Hi reshma,it is the 1/r^3 which is the correct answer.Note that it is a quadrupole...You may wish to refer to Griffiths page 147.
  4. Dec 3, 2007 #3
    Thanks a billion, neelakash! I knew something was fishy with my answer...I never thought of the quadrapole moment.
  5. Dec 3, 2007 #4
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