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Homework Help: Why is the e field 0?

  1. Sep 6, 2011 #1
    1. The problem statement, all variables and given/known data
    An inner conductor has radius 1.5cm and linear charge density 6 nC/m and the outer conduct has no net charge. The outer conductor has radius 4.5cm and 6.5cm.
    Find the e field for all values of R where R is the perpendicular distance from the common axis of cylindrical system.

    In the book they had that E=0 for r<1.5cm.
    Why is that, shouldn't E=0 if it was a hollow conductor. In this case the book is drawing the conductor has a solid cylinder, not a hollow one. The big conductor is hollow with the 2 radius but not he smaller one. Can someone explain this to me.

    Edit-I think they assumed the charge would be 0 for r<1.5cm
  2. jcsd
  3. Sep 6, 2011 #2


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    Hmm I think I would need to see a pic to make sure I fully understand what the object is. You should be able to use Gauss for each situation in these types of problems.
  4. Sep 6, 2011 #3


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    If there is a non-zero field within a conducting material, what will happen to the charges which are free to move?
  5. Sep 6, 2011 #4
  6. Sep 7, 2011 #5
    ask urself what will happen if there is an electric field set up within a conductor. what will happen to the charges?
  7. Sep 7, 2011 #6
    In a conductor the charge is on the surface. Hence E will be zero
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