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Homework Help: Electric Field at Point Z, Two Charges

  1. May 26, 2009 #1
    1. The problem statement, all variables and given/known data

    I have drawn the diagram on the attached page... IT contains all information. The question is simply to determine the electric field force at point Z (which is at the very upper edge of the page)

    2. Relevant equations

    epsilon= Fe/q

    3. The attempt at a solution


    I just noticed I forgot to square root the radius (rAZ and rBZ) in the top right corner.. that changes my answer, but not to the right answer.... Now I get 1.44*10^5 . Correct answer is 1.21*10^5

    What's wrong :S
    Last edited: May 26, 2009
  2. jcsd
  3. May 26, 2009 #2
    I think it should be sin(90 - theta), not sin(theta)
  4. May 26, 2009 #3
    woah... woah... why? tan(theta)=.04/.03 ... that's unarguable... that gives my radius...

    And in the Y-component part, we are taught to use sin(theta) for Y-components, where theta is the angle from the positive x-axis.
  5. May 26, 2009 #4
    Sorry, I confused sin with cos :S

    Edit2: I keep getting 1.15 * 10^5
    Last edited: May 26, 2009
  6. May 26, 2009 #5
    Figured it out... I dropped the sin(53.13) when I multiplied by 2... but to answer your question, sin(180-theta)=sin(theta)
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