Re: Confused by a derivation.

[John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>]

One more thing.  The problem is surely *much* easier than any of
us have made out if we are willing to specify that there are no
other charges in the universe. In that case there simply can't be
any field outside the capacitor since there is no place for the
field lines to end.  Since there is no place for them to end, they
can't start.  Hence, no charge is allowed on the outer surfaces.

John Mallinckrodt      mailto:ajm@csupomona.edu
Cal Poly Pomona          http://www.csupomona.edu/~ajm

On Tue, 5 Feb 2002, John Mallinckrodt wrote:

> On Tue, 5 Feb 2002, Bob Sciamanda wrote:
>
> > Sure, John.  But the statement of this problem says there is no
> > pre-existing background field.  The four layers of charge are here the
> > entire universe.
>
> Oh.  Oops.  I didn't remember seeing that specification.  I guess
> I am the only one making mistakes around here!