Re: how many volts ?

["W. Barlow Newbolt" <wnewbolt@liberty.uc.wlu.edu>]

On Wed, 26 Mar 1997, Donald E. Simanek wrote:

> On Wed, 26 Mar 1997, W. Barlow Newbolt wrote:
>
> > I think that we beginning to make this problem difficult.  We can 
> > probably calculate the potential distribution is space due to a flattened 
> > coffee can lid isolated in space with 100nC on it.  We can do the same 
> > for one with -10nC on it.  The charge will probably be distributed so 
> > that both plates have an excess of charge at the edge.  The appropriate 
> > derivatives will yeild the field.
> >
> > Now we have to move them together.  Presumably, the charge distributions 
> > will change and the plates will attract one another during the move.  I 
> > have no idea how to model the changes in the potential.  Apparently, the 
> > potential at infinity would approach that of a point charge with 90nC and 
> > a capacitor with +10nc on one plate and -10nC on the other.  The latter 
> > will probably fall off much faster than the former--does that help?
>
> John already gave a correct solution, much simpler than this, and it got
> tidied up a bit by a few subsequent posts which confirmed the logic and
> insight. Seems to me the problem as originally given, is done. The
> considerations you discuss above simply aren't necessary for doing the
> problem as given.
>
> Perhaps someone (John?) should restate the problem and its solution in
> polished form with all the necessary insights, so we can close this epsode
> and move on to something completely new. It's unclear to me whether some
> people are disagreeing with the solution, or the method for obtaining it,
> or perhaps some didn't understand it.
>
> 	-- Donald
>
> .....................................................................
> Dr. Donald E. Simanek                            Office: 717-893-2079
> Prof. of Physics                    Internet: dsimanek@eagle.lhup.edu
> Lock Haven University, Lock Haven, PA. 17745          CIS: 73147,2166 
> Home page: http://www.lhup.edu/~dsimanek            FAX: 717-893-2047
> .....................................................................
Hey, Donald.  I'm just trying to talk about the case when all of the 
field lines do not stay perpendicular to the plates--finite sized plates. 
I think that is what Ludwik wanted us to talk about.  I agree that John 
has completely and elegantly solved the case for infinite plates.

W. Barlow Newbolt              540-463-8881  (telephone)
108 Parmly Hall                540-463-8884  (fax)
Washington and Lee University  newbolt.w@fs.science.wlu.edu	
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