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Homework Help: Calculating the magnitude of point charges

  1. Sep 12, 2010 #1
    1. The problem statement, all variables and given/known data
    A point charge of -6 µC is located at x = 1 m, y = -2 m. A second point charge of 12 µC is located at x = 1 m, y = 3 m.

    (a) Find the magnitude and direction of the electric field at x = -1 m, y = 0.

    (b) Calculate the magnitude and direction of the force on an electron at x = -1 m, y = 0.

    2. Relevant equations

    3. The attempt at a solution

    [tex]\Sigma_{F}= k\frac{-6 \mu C}{8} + k\frac{12 \mu C}{13} = 1.08e4 \frac{N}{C}[/tex]

    That's for the magnitude part of A. I've already submitted to many incorrect responses, but I would like to know how to do it. Thanks ahead of time.
  2. jcsd
  3. Sep 12, 2010 #2


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    Homework Helper

    You need to find both the x and y components from each charge at the point of interest and add them up accordingly to find the resultant field.
  4. Sep 12, 2010 #3
    I did that for another problem that asked for the respective components, why is it necessary that I so that for this problem?
  5. Sep 12, 2010 #4


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    Homework Helper

    Since I don't know what the other question was, I can't tell you what's different. You need to do vector components because the point of interest is not on the same line as the two charges. It is a two dimensional situation. Have you tried what I suggested?
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