Re: Electrostatic shielding

[Bob Sciamanda <trebor@VELOCITY.NET>]

My senility is vascillating on this question. . . Some random thoughts:

1) The charges will settle to an arrangement in which the conducting
material is an equipotential volume (E=0) under the combined effects of the
three items, the imposed charge, the inner surface charge and the outer
surface charge.
2) In the case of the single imposed charge centered inside a hollow,
conducting sphere the imposed central charge and the inner surface charge
alone accomplish this as a pair, and the outer surface charge also does so
(contributes zero E and constant V throughout the conducting material).

3) Two questions:

a) If the imposed charge moves off center will the inner surface charge
still settle so that it and the imposed charge still (as a pair) contribute
zero E in the conducting material.  If so, the outer surface charge must
still contribute zero E (constant V) and so will not be re=arranged.

b) If a) is so for the sphere, is it true for the generally shaped hollow
conductor enclosing a fixed imposed charge.   IE, in the general case do the
inner surface charge and the imposed charge alone (as a pair) effect E=0
(and V= Constant) inside the conducting material.  If so, the outer surface
charge must take the unique arrangement which alone also gives E=0 (V=Const)
regardless of the position of the imposed charge.

I am presently inclined to believe that both a) and b) are so . . . I now
seek some sleep and hope to awaken to someone's proof (or contrary
argument).

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
www.velocity.net/~trebor
----- Original Message -----
From: "Bob Sciamanda" <trebor@VELOCITY.NET>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, January 31, 2001 10:54 PM
Subject: Re: Electrostatic shielding


> ----- Original Message -----
> From: "Lemmerhirt, Fred" <FLemmerhirt@MAIL.WCC.CC.IL.US>
>
> > , , ,
> >  I can't seem to come up  with the condition that requires the outer
> positive charge
> > to remain uniformly distributed.  . . .
>
> I can't either, because it is not true that the outer charge layer will
not
> be re-arranged.
>
> Bob Sciamanda (W3NLV)
> Physics, Edinboro Univ of PA (em)
> trebor@velocity.net
> www.velocity.net/~trebor