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Homework Help: Electrostatic induction (can someone check my answer?)

  1. Aug 13, 2009 #1
    1. The problem statement, all variables and given/known data
    Three identical metal spheres are supported on three insulating stands.A charge q is given on the first sphere .The first sphere is then momentarily touched with the second sphere and then the second sphere is momentarily touched with the third.
    Finally the third sphere is momentarily touched with the first again.
    The final amounts of charge residing on the first,second and the third spheres respectively are...?

    2. Relevant equations

    3. The attempt at a solution

    I think in the first case,
    when the 1st sphere touches the 2nd,a charge of q/2 passes on to sphere 2 and a charge of q/2 remains on sphere 1
    Then when sphere 2 touches sphere 3,a charge of q/4 moves to sphere3 and q/4 remains on sphere 1,
    And when,sphere 3 touches sphere 1 again,the total charge is now q/2 + q/8 i.e 3q/4,
    so sphere 1 and sphere 3 now have a charge of 3q/8 each ?

    Thanks in advance !
  2. jcsd
  3. Aug 13, 2009 #2


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    Looks OK to me.
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