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Homework Help: 3 Charges

  1. Jun 28, 2010 #1
    1. The problem statement, all variables and given/known data

    A negative charge Q1 = -8 nC is fixed on the x-axis at (x = -4, y = 0). A positive charge Q2 = +8 nC is fixed on the x-axis at (x = 4, y = 0). For the sake of reference, consider point A, at (x = 0, y = 5). All locations are in meters.

    What is the sign of the x-component of the electric field at A?

    What is the sign of the y-component of the electric field at A?

    What is the magnitude of the electric field at A?

    A third charge (q = 4 nC) is brought in from very far away and put at point A. What total potential energy is stored in all three charges?

    2. Relevant equations



    3. The attempt at a solution

    I'm reviewing for an exam and I just dont know how to answer these questions. Any explanation would be appreciated. Thank You
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jun 29, 2010 #2
    Start by drawing it out on paper. Perhaps you will notice some sort of symmetry between the two charges and the point A.
     
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