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Homework Help: Problem with electric forces

  1. Jan 10, 2005 #1
    Hello all. I am kindof stuck on this problem. It asks: The figure below shows three point charges all posotive. If the net electric force on the center charge is zero, what is the value of y/x.
    The answers:
    a) 4/9
    b) [tex] \sqrt{2/3} [/tex]
    c) [tex] \sqrt{3/2} [/tex]
    d) 3/2
    e) 9/4

    This is my figuring:

    [tex] K\frac{2q}{x^2} - K\frac{3q}{y^2} = 0 [/tex]

    But how can I get an actual number without a value for q?

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  2. jcsd
  3. Jan 10, 2005 #2


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    You can divide the whole equation through [itex] \frac{1}{4\pi\epsilon_{0}\epsilon_{r}}=:K [/itex] and "q" and then try to see which numbers fit the equation left...

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