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Re: communicating charges



Your conclusion is not generally true. Radiation is generated
by accelerated charges. As I keep repeating, the coulomb field is not
transmitted by photons. If the charge that moved is in uniform motion
then there is no radiation.
There is, however, an interesting effect connected with charges
in uniform motion at speeds close to the speed of light. The coulomb
field picks up a transverse component and, by Lorentz transformation,
a B-field, so that the field resembles a radiation field. This effect
is discussed in Chapter 15 of Jackson's book. The names connected with
this effect are Weiszacker and Williams - their work was done in the
'30's.
Regards,
Jack


Adam was by constitution and proclivity a scientist; I was the same, and
we loved to call ourselves by that great name...Our first memorable
scientific discovery was the law that water and like fluids run downhill,
not up.
Mark Twain, <Extract from Eve's Autobiography>

On Sun, 24 Sep 2000, David & Shimako Piazza wrote:

I need some verification or correction on my thinking about
charges and electromagnetic waves. Please comment on the veracity of
the following:

Imaging a flat coordinate plane with a positive charge at (0,0)
and a negative charge at (1,0). With this arrangement, there is a
force exerted on the negative charge by the positive charge, I'll call
F_on_neg.

If the positive charge is moved from (0,0) up to (0,1), then
F_on_neg will now point in a new direction. Of course there was some
time delay between the motion of the positive charge and the
corresponding adjustment of the direction of F_on_neg. In effect, time
was needed for a signal to be sent from the positive charge to the
negative charge to communicate the new position. This signal is an
electromagnetic wave.

Is what I have said true?


Thanks,

David Piazza
HS Science Teacher
The Branson School, CA