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Determining point where net electric field is zero

  1. Oct 2, 2014 #1
    Hello comrades,

    Question

    A negative charge of 3.00 mC is 1.20m to the right of another negative charge of 2.00 mC. Calculate the point along the same line between the two charges where the net electric field will be zero.

    Formulas

    E=kq/r2

    Attempt at Solving

    Well, I get as far as setting E1=kq/r2 equal to E2=kq/r2 but am at lost as to what to do next. I tried bringing the equations all to one side and setting them equal to zero but can't seem to isolate for r. I also tried cross multiplying and dividing but didn't get the answer from that either. I know the answer (0.661m left of the -3.00 charge) but am unable to find out how to get the answer. If someone could provide a detailed, comprehensive explanation as to how to figure this question out it would be greatly appreciated.

    Cheers!
     
  2. jcsd
  3. Oct 3, 2014 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

    The q's are not the same.
     
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