I saw the electrostatic shielding postings on this list in 2001 concerning
hollow spheres with a charge at the center of the sphere. I agree that a
positive charge within a hollow metallic sphere induces an equal negative
charge on the inside surface of the metallic sphere.
Then a positive and equal charge is present on the outer surface. The net
electric field inside the sphere is zero. The outside surface has a field
just like the interior positive charge and as if the metallic sphere was
not there at all. My sphere is not grounded to the earth.
My first question is this, "What happens to the charges if you drill a
small hole in the sphere? I think the outer equipotential spherical
"lines" dip into the aperture and distorts the outer electric field but no
much more happens. You would see this dip in a physics book as a parallel
plate capacitor's edge fringing equipotentials or electric line fringes.
You have not changed the interior charge(s) by drilling a hole. This
question would be similar to a braided 80% shielded wire cable case but
with one hole, I think.
I can't drawn a sphere or balance the charges with a keyboard but this is
the idea ....
I guess you might think that the outside charge would flow inside and
neutralize the hollow metallic sphere but I don't think so. I might
believe eddy currents flow like that but the charges will not neutralize,
my postulation. The positive central charge will keep maintaining the
inside negative charge because the central charge never "goes away".
Any resemblance of my down arrow to a compound pendulum with a hole in it
is purely coincidental.