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Re: Charged disk; was electrostatic ...

A fairly common misconception is that 'most' of the charge will
collect on the more sharply curved surface, (needle tip). A closer
analysis will indeed show that the charge DENSITY is quite large on
the highly curved surface, but the small area involved does NOT lead
to a preponderance of charge being on the tip. Corona discharge has
been ruled out in this discussion of an 'isolated' object. Lightning
rod tips are NOT isolated and do indeed exhibit coronal discharge.

At 8:47 PM -0500 2/4/01, Ludwik Kowalski, you wrote about Re:
Charged disk; was electrostatic ...:

Start with a
metallic sphere which has some charge Q. It is uniformly distributed
over the smooth surface. Now supply the same Q to another sphere
of the same radius which but has a sharp needle sticking out.
Will most of the Q be concentrated near the sharp point? I would say yes.
^^^^ ^^ ^^^ ^ ^^ ^^^^^^^^^^^^

Each sharp edge of a cylinder is like a set of many needles. But
I am not at all certain that this is correct because curving along the
edge is much less rapid than curving across the ridge.

Doesn't this discussion remind you of a medieval debate on
how many angels can reside ...? We need a 3-D simulation.
Ludwik Kowalski

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