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Homework Help: Question about coulomb's force.

  1. Mar 1, 2009 #1
    1. A certain charge "Q" is to be divided into two parts, "Q-q" and "q". What is the relation of "Q" to "q" if two parts, placed at a given distance apart, are to have the maximum coulomb's repulsion?

    I am unable to find the condition when there is a maximum Coulomb's repulsion. Any help will be greatly appreciated.

    Thanks in Advance

  2. jcsd
  3. Mar 1, 2009 #2
    What have you tried so far?
  4. Mar 1, 2009 #3


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    Homework Helper

    Write down the expression for the force between the charges. Find the differentiation with respect to q and equate it to zero. That gives you the condition for the maximum coulomb's repulsion.
  5. Mar 1, 2009 #4
    Why find the differentiation with respect to q and then equate it to 0? I mean why force will be maximum when we do this? Can anyone explain? Moreover, whether we differentiate the expression with "Q" or "q"?
    Last edited: Mar 1, 2009
  6. Mar 1, 2009 #5
    Now I have found what is the reason. Thank you very much for help rl.bhat.
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