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Homework Help: Gauss law for cilynder

  1. May 17, 2006 #1
    So question :
    We have cored cilynder. Inner radius 10 cm, outer radius 20 cm. In the walls
    of the cilynder uniformed charge 2nK/m^3. Find electric field magnitude at the points from axes 8cm 18cm 28cm.

    Sorry for my english.
  2. jcsd
  3. May 17, 2006 #2
    I think you mean 2 nC/m^3 for the charge density. What attempts have you made in solving this problem. The first case is the easiest.
  4. May 17, 2006 #3
    Yes I mean nC/m^3. So For 8cm I think to use that E = <r0>*r\(2*e*0e).
    it is a case then point where we define electric field is inner cilinder.
    But then we have 18cm, then point would be in the cilinder.
    3 case i could use E = <ro> *R^2\(2*e0*e*r), but what should be R - radius od cilynder 20cm.

    <ro> is charge density.
  5. May 17, 2006 #4
    For the first case, the gaussian cyclinder would enclose no charge at all. Now for the other two, draw similar gaussian cylinders - one within the walls and the thrid outisde the charged cylinder. If you know the general case of evaluating the field of a long cylinder using Gauss' law, it would be a simple exercise to solve the problems.
  6. May 17, 2006 #5
    EDIT: Never mind...I was being an idiot!
  7. May 17, 2006 #6
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