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Electric Potential

  1. Jun 1, 2009 #1
    1. The problem statement, all variables and given/known data

    A point charge of +8C is located at (-6,0)cm. A second point charge of -11C is located
    at(-5,-12)cm. If a -5C charge were at the origin, how much energy is required to move it to in nity?

    2. Relevant equations

    V=KQ/R
    U = -qV


    3. The attempt at a solution
    I have the solution. It is given as below... I just dont understand why!
    http://a-s.clayton.edu/jdyer/physics/phys1112/phys1112S09/Quizzes/1112_Quiz2_solution.pdf" [Broken]

    If the origin now has a -5 micro C charge, why is the energy potential still calculated as if it was not there? I have been banging my head on this for a while, any help would be greatly appreciated.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Jun 1, 2009 #2

    rl.bhat

    User Avatar
    Homework Helper


    V1 and V2 are the potentials at origin due to two charges. -5 μC charge is taken from origin to infinity and the work done to do this is -q*ΔV.
     
    Last edited by a moderator: May 4, 2017
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