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Homework Help: Electrostatics - probably a standard question

  1. Apr 18, 2013 #1
    Q) A solid non-conducting sphere of radius R carries non-uniform charge distribution with charge density ρ = ρs(r/R), where ρs is a constant. Show that
    (a) the total charge on the sphere is Q = ∏ρsR3, and
    (b) find the electric field inside the sphere.

    Now first part (a) is fairly easy,
    assumed a sphere of radius x and then after further integration got the result

    But i need an idea for the second part..
    since there is no symmetry so "Gauss" theorem is of no use applying...
    I think i need an integration there as well. But can someone provide me an idea on how to continue further. Thanks in advance.
  2. jcsd
  3. Apr 18, 2013 #2


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    Staff: Mentor

    There is a spherical symmetry.
  4. Apr 18, 2013 #3
    How did you get the answer to part a. It seems incorrect to me.
  5. Apr 18, 2013 #4
    Never mind, I got it.
  6. Apr 20, 2013 #5
    what about the electric field?
  7. Apr 20, 2013 #6


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    Science Advisor
    Homework Helper

    Use Gauss' theorem. Find the charge enclosed in a radius r'<R. Use integration.
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