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Homework Help: Electric Fields

  1. Mar 6, 2015 #1
    1. The problem statement, all variables and given/known data
    Attached below

    2. Relevant equations
    E = [kq/r^2]r -------> r is the unit vector

    3. The attempt at a solution
    I did the same thing as the solution below, however, I do not understand why there is root-2 in the denominator. I would appreciate it if someone could explain this to me.

    Attached Files:

  2. jcsd
  3. Mar 6, 2015 #2
    How would you express the unit vector going from each Q to point P?
  4. Mar 6, 2015 #3
    it would be E=[kQ/d^2]i
  5. Mar 6, 2015 #4
    That's for one of the Q's. What about for the other one?

    Note that it's essential to make sure you have set up a clear coordinate system for the problem.
  6. Mar 7, 2015 #5
    It would be E=[kQ/2d^2](-cos45i+sin45j)
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