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Homework Help: Electric Field caused by two charges problem

  1. Aug 28, 2014 #1
    1. The problem statement, all variables and given/known data
    Two identical point charges, q1 = +2.5 x 10-6 C and q2 = +2.5 x 10-6 C, are placed as shown in the diagram below. Point P is a distance 0.05 m from q1 and 0.12 m from q2, such that the angle at P is 90 degrees. Calculate the magnitude of the Electric field E at point P.

    Electric Field Magnitude Problem.jpg

    2. Relevant equations

    Not sure which of these rules would apply. Also I suck at vectors
    F = k x q1 x q2 / r^2

    E = k x Q / r^2

    3. The attempt at a solution

    So I have created the diagram and I believe I have to use the second formula twice, along with some trigonometry, but I'm not sure.
    Last edited: Aug 28, 2014
  2. jcsd
  3. Aug 28, 2014 #2


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    I feel you could make a better stab at figuring out which of those equations are likely to be relevant.
    Do you know how to determine the field at a point due to a charge at some other point?
    Do you know how to add vectors?
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