On 6 jul, 19:07, K1TTT wrote:
On Jul 6, 5:23*am, Keith Dysart wrote:





On Jul 5, 9:57*pm, Cecil Moore wrote:

On Jul 5, 7:44*pm, Keith Dysart wrote:

When, exactly, does the EM wave cease to exist?

I don't know exactly but it will be when DC steady-state has been
achieved, i.e. when electrons are no longer being accelerated or
decelerated.

More evasion. So are now saying there may indeed be an EM wave
present with DC? Even with DC, the electrons are not moving with
constant velocity but hop from atom to atom. Seems like
acceleration and deceleration to me.

...Keith

DC does not an EM wave make... nor does one year make DC, the
summation is infinite, you must wait FOREVER for DC to be achieved and
by then you just won't care any more.- Ocultar texto de la cita -

- Mostrar texto de la cita -

Hello friends:

A few years ago I posted in this newsgroup a doubt from a friend of me
about DC current (such a batery connected to a lamp) radiating EM
waves... It was in topic "Antenna gain question" (2005-10-31). My
answer wold be that classic physics postulate EM radiation from
accelerated charges in closed circuit because charges are under
centripetal acceleration (I though of ciclotron radiation analogy, of
course). My friend Richard Clarke disagreed with my hypothesis and I
archived the issue for a couple of years, (he give me some analogies
with moving cars, I remember...)

Time later I was casually reading some pages from Kraus and I found
the answer! :D: Kraus says: "a charge moving at uniform velocity
along a curved or bent wire it is accelerated and radiates".
The clue was in words "straight wire" , he says: "Electric charge
moving with uniform velocity along a straight wire does not radiate".
then, a DC also must be rectlinear (perhaps it must move on a
geodesic, but I do not know general relativity enough to say it) (*)

(*) "Antennas" John D. Krauss - Second Edition -1997 Page 50.

73 - Miguel Ghezzi - LU6ETJ