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Homework Help: 2 test charges

  1. Sep 17, 2007 #1
    1. The problem statement, all variables and given/known data
    Two test charges are brought separately into the vicinity of charge +Q. First the test charge +q is brought to a point A, a distance r from +Q. Next, +q is removed and a test charge +3q is broguht to a point B, a distance 2r from +Q. Compared with the electric potential of +Q at point A, that of +Q at B is how much that of A. The choices are tiwce that of A, 1.5 times, the same as A, half of A, or 3/4 that of A



    2. Relevant equations
    I was using the equation kq/r for electric potential and plugging in numbers but I'm unsure what to else to do.


    3. The attempt at a solution
     
  2. jcsd
  3. Sep 17, 2007 #2

    dynamicsolo

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    Homework Helper


    OK, this is a sneaky one. Be careful about the fact that they are asking about the electric *potential* of the +Q charge at points A and B. You have the correct formula for the potential, so what should you write for each part of the comparison?
     
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