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Can you please check my answers?-Gauss's Law

  1. Feb 9, 2007 #1
    would you please check my answers?-Gauss's Law

    1. The problem statement, all variables and given/known data

    I've just had an exam and this was one of the questions.
    There is point charge Q1 = -6C in the center of conducting shell. The total amount of charge on the shell is 4C. Then, outside the shell there is point charge Q2=-8C and there is another metal shell enclosing all this. The total charge on the outer shell is also 4C.

    Questions are:
    1) Electric field between the inner most shell and Q1
    2) Charge on the inside surface of the inner shell?
    3) Charge on the outside surface of the bigger shell?
    4)Electric field outside the big shell?

    3. The attempt at a solution

    I got these answers:
    1) by Coulomb's law E = kQ1/r^2 where r is the distance from Q1

    2) to cancel 6C of Q1 there is -6C

    3) there is also -6C on the outside of big shell since there is +10C on the inner surface of that shell

    4) using Gaussian sphere around everything I got
    E = -6k/r^2 where r is radius of the sphere

    So, can you please tell me if my answers are correct?
    Last edited: Feb 9, 2007
  2. jcsd
  3. Feb 9, 2007 #2
    relax, wait for the grading, have some fun. if you're then stuck, come again.
  4. Feb 10, 2007 #3
    OK, thank you, but if it was fun waiting I wouldn't have asked the question at all.
  5. Feb 10, 2007 #4


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    I think denverdoc's response might have been different if he had found any problems with your solution.
  6. Feb 10, 2007 #5
    Thanks Dick, I hope you're right.
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