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Homework Help: Electrostatic force including coulombs law

  1. Aug 27, 2008 #1
    1. The problem statement, all variables and given/known data

    Of the charge Q initially on a tiny sphere, a portion q is to be transferred to a second, nearby sphere. Both spheres can be treated a particles. For what value of q/Q>0.5 will the electrostatic force between the two parts have 1/2 of the maximum possible value?

    3. The attempt at a solution

    ok i drew a picture and i know that sphere 1 is Q-q , and sphere 2 is q, and i plug into equation


    i differentiate and get qQ-2q now what i do from here, to get 1/2 maximum possible value

    i know to get maximum i set equal to zero, do i set this equal to 1/2? How would i solve it for q/Q ratio if its equal to 1/2?
  2. jcsd
  3. Aug 27, 2008 #2
    Q is a constant. just set it equal to 1. same with r.
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