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Re: Surface charge distribution



Hi-
The only response that I saw just gave an answer without an
explanation. I suggest that the reverse would be a better practice.
A charge is placed off-center inside a spherical conducting shell.
Find the field outside of the shell.
The issue is: what is the meaning here of (perfectly) "conducting
shell"?

What is meant is that that the positive and negative charges in the shell
are free to position themselves so that no currents flow in the shell.
This requires that the positive charges all get pulled to the inner
surface, the negative charges are pushed to the outer surface, and the
charges distribute themselves uniformly - that's the key, uniformly - over
each surface. Uniformity is required to avoid currents running along the
surface.
Note that a spherical Gaussian surface that lies completely within
the shell (that is, between the inner and outer surfaces of the shell) is
in a field-free region. The net charge enclosed is zero.
A similar surface outside of the outer surface of the shell must
then enclose a net charge equal to the charge that was place inside (of
the inner surface) of the shell.
Regards,
Jack

On Tue, 3 Dec 2002, Fakhruddin, Hasanbhai wrote:

Hello Everyone!

Need help with the following conceptual problem:

A conducting shell is initially neutral. A point charge +q is placed
OFF CENTER inside the cavity. Is the charge induced on its outer
surface symmetric or asymmetric? =20

Thanks,=20

Hasan Fakhruddin
Instructor of Physics
The Indiana Academy for Science, Mathematics, and Humanities
BSU
Muncie, IN 47306
E-mail: hfakhrud@bsu.edu


--
"What did Barrow's lectures contain? Bourbaki writes with some
scorn that in his book in a hundred pages of the text there are about 180
drawings. (Concerning Bourbaki's books it can be said that in a thousand
pages there is not one drawing, and it is not at all clear which is
worse.)"
V. I. Arnol'd in
Huygens & Barrow, Newton & Hooke