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Electric field and gauss law for different models of sphere

  1. Apr 17, 2013 #1
    Hello all!!! I actually have a few doubts regarding "gauss law" when applied "for different models of sphere"

    First, If we place a charge 'Q' inside a spherical shell at the center (somehow) then it should come out to its surface that means in no way can we do it. True or False????


    Considering a solid sphere having a charge Q uniformly distributed on its outer surface. Thus everywhere inside it is the electric field equal to 0.

    But i have somewhere read that the electric field inside a solid sphere is Kqr/R^3.

    Or is it that , there is a difference in these two statements
    "A charge uniformly distributed on the surface of a solid sphere" and
    "A symmetrical spherical distribution of charge" ????

    Also, How can we get a spherical symmetrical distribution of charge?
    . By placing the charge at the center of the solid sphere???? (which is again impossible i guess)

    I'll be greatly thankful if someone clears these brain storming doubts?
  2. jcsd
  3. Apr 17, 2013 #2


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    hello exuberant.me!!! :smile:

    (try using the X2 button just above the Reply box :wink:)
    sorry, no idea what you mean :redface:
    yes … Kqr/R3 is for a charge uniformly distributed throughout the volume (use gauss law! :wink:)
    no, by chucking the charges in, and giving them a good old stir

    like making a pudding :smile:
  4. Apr 17, 2013 #3


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    Staff: Mentor

    With no lumps, of course... nice and smooth...
  5. Apr 17, 2013 #4


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    [tex]\frac{\partial \rho}{\partial \theta} = \frac{\partial \rho}{\partial \phi} = 0 [/tex]
    and practically how this could happen for a solid sphere with fixed charges? ...err... maybe in Neutron stars that have a surplus of electrons? The electrons wouldn't be fixed, but in equilibrium the charge distribution would be spherically symmetric... unless it was a pulsar?

    So you just have to make a neutron star :) easy-peasy.
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