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Homework Help: A charge inside a non conducting spherical shell uniformly charged

  1. Jun 3, 2012 #1
    This problem is driving me mad
    suppose that we have a positive charge inside a non conducting spherical shell uniformly charged
    the charge is at a random place inside the shell but not in the center
    the text book says the charge will feel no force from the charges of the shell and the argument is based on gauss law when there's no charge inside the shell
    this is true but when we put the charge inside everything changes
    if we apply gauss law
    we choose a gaussian surface that has the same center as the shell with a radius that's big enought to contain only the emptiness before the charges of the shell (if we can say that)
    so there will be an electric field that will act on the charges
    so either the charge moves or the shell moves
    this is what i could conclude
    please tell me where did i go wrong
  2. jcsd
  3. Jun 3, 2012 #2
    I apologize for not following the pattern cause this isn't really a problem just a case that was mentioned in the lecture and i didn't understand
  4. Jun 4, 2012 #3

    rude man

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    I'm confused as to what the situation is.

    If there is only 1 charge inside the charged shell, the force on that point charge is zero, since the shell charges' effects cancel each other at the inside charge no matter where that charge is located. This is what your problem seems to state.

    What you say after that I can't follow. If you assume two (or more) charges within the charged shell then those inside charges will attract or repel each other but still none of those inside charges will be affected by the charged shell.

    It's no different than the fact that a uniformly dense spherical shell does not generate a gravitational force inside the shell. The shell simply does not exist as far as masses inside the shell are concerned. And it's exactly the same situation with the charges, since electrostatic and gravitational forces both vary inversely as the square of the distance.
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