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Homework Help: Multiple Point Charges

  1. Nov 2, 2008 #1
    A charge of 1.2x10^-3C is fixed at each corner of a rectangle that is 30cm wide and 40cm long. What is the magnitude and direction of the electric force on each charge? What is the electric field and the electric potential at the centre?

    This is the question i am currently trying to solve. This is what i have so far.

    sqr(0.3^2+0.4^2) = 0.5
    tan(0.3/0.4)= 36.87 degrees

    Vector force on q1 upper right:
    9*10^9*(1.2*10^-3)^2/(0.3)^2 = 144000 N @90
    9*10^9*(1.2*10^-3)^2/(0.4)^2 = 81000 N @0
    9*10^9*(1.2*10^-3)^2/(0.5)^2 = 51840 N @36.87

    Adding the vectors, i now need to know how to find the forces of each charge and the cooresponding angles. Any help will be appreciated.
  2. jcsd
  3. Nov 2, 2008 #2
    any help would be appreciated.. please and thank you
  4. Nov 2, 2008 #3
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