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Homework Help: Using 5 point charges, finding the charge of q1 and q2 using given force

  1. Jan 25, 2012 #1
    1. The problem statement, all variables and given/known data
    The figure shows five point charges placed on a line, at intervals of 1 cm. For what values of q1 and q2resultant electrical force exerted on each of the three charges is zero?
    11.gif

    2. Relevant equations
    I imagine the law of coulomb is used here, however, I'm not sure how I'm supposed to tackle this one, since the resulting force on the given charges is zero. I guess, it gets confusing when you add more than 2 charges. Anyway, anyone have any hints to help me figure this one out?


    3. The attempt at a solution
    Haven't got an idea
     
  2. jcsd
  3. Jan 25, 2012 #2
    It's the same as adding 2 forces except now you're adding 4!

    Think about what direction each force is acting on and draw some pictures. You know that the total force = 0. In other words. The forces acting to the left have to cancel out the forces acting to the right.
     
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