Re: Gauss law again

[John Denker <jsd@AV8N.COM>]

Quoting Ludwik Kowalski <kowalskil@MAIL.MONTCLAIR.EDU>:

> Why am I asking this question?

Much appreciated.  It is always good to explain why
a question is being asked.  Often the hard part of
answering a question is figuring out where the other
guy is coming from.

>  A small additional displacement
> already resulted in a change of density at the
> right side. But the left side "was not yet
> informed" that the displacement occurred.

1) If this small additional displacement is part of a
steady *unaccelerated* motion, the message to "inform"
the left side was sent long ago, by the previous motion
of the source.  The message will arrive just in time,
no problem.

2) If this small additional displacement results from
an acceleration, i.e. it is not consistent with a
simple extrapolation of the previous motion of the
source, then this is a verrrrry interesting question.
If you analyze it closely enough, you will re-discover
the radiation law.  The field lines (to the extent that
they exist at all) will still start on the source charge
and end on the countercharge on the enclosure, 100%
consistent with the Gauss/Coulomb law ... but they will
not be straight, i.e. not consistent with your electrostatic
intuition.  As the acceleration becomes more and more
sudden, there will be a more and more impressive kink in
the field.

http://www.google.com/search?q=field+accelerated-charge
http://colos1.fri.uni-lj.si/~colos/COLOS/TUTORIALS/JAVA/JAVAXYZET/ELECTRICITY/electrostatics1.html