I know that inside the body of a homogeneous isotropic conductor the field is effectively zero and so I'm wondering what happens on the outer surface of a hollow conductor of total charge $q$ when we place a point charge $-q$ in its void. Is the charge going to be zero on the outer surface? And if it's zero, does the positive and negative charges spread uniformly or accumulate within regions to make the field zero in the body of the conductor, say in a conducting spherical shell?

  • $\begingroup$ You probably know this already but, charges do not flow freely through insulators so I doubt that any charges would reach the surface from the inside. If that helps. :) :) :) :) :) $\endgroup$
    – Max
    Oct 18, 2021 at 16:31

1 Answer 1


As long as the hollow conductor has thickness, the total amount of charge $+q$ on the outer surface migrates to the inner surface after $-q$ has been inserted in the cavity. That'll be still consistent with the Gauss' Law.

  • $\begingroup$ In this case there will be no charge on the outer surface and no electric field will exist outside the spherical shell, correct? $\endgroup$ Oct 18, 2021 at 17:50
  • 2
    $\begingroup$ No fields within the conductor and outside the sphere. Fields only appear in the cavity only. $\endgroup$ Oct 18, 2021 at 17:52

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