"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?

Not EM but the electric wave.
In the free electron laser (halbach array) is DC and waves are produced.

Even with DC, the electrons are not moving with
constant velocity but hop from atom to atom. Seems like
acceleration and deceleration to me.

If the electron beam is periodically deflected the current is DC but the all
works like the dipole.
S*