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Homework Help: Find mag. of net electric field at the center

  1. Feb 4, 2012 #1
    1. The problem statement, all variables and given/known data
    A point charge is placed at each corner of a square with side length a . The charges all have the same magnitude . Two of the charges are positive and two are negative, as shown in the following figure.

    my figure: (image each charge represents a corner of the square)

    What is the magnitude of the net electric field at the center of the square due to the four charges in terms of q and a ?
    Express your answer in terms of the variables q, a, and appropriate constants.

    2. Relevant equations

    3. The attempt at a solution

    I uploaded my work as an attachment..I'm getting the wrong answer. The correct answer is E=(4kq√2)/a2, whereas I kept getting E=(kq√2)/2a2

    any ideas? thanks

    Attached Files:

  2. jcsd
  3. Feb 4, 2012 #2


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    Staff Emeritus
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    You need to keep only the y -component of the electric field due to each charge.
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