On Sun, 07 Sep 2003 10:48:46 -0700, Ken S. Tucker wrote:

"Pmb" wrote in message ...

"Bastian" wrote in message
. com...
My Professor used to ask this question in oral exams: What happens if
an elektron falls off from a table? Usual answer: The elektron is an
accelerated charge and so it radiates elektromagnetic waves.
I argued that an elektron would not radiate when accelerated by an
gravitational field.

I agree with you, (but I also agree with Pmb as he reconditioned
the set-up). An electron accelerated by a g-field alone and in a
zero electrostatic and magnetic field will not radiate.

In classical terms, Maxwell's radiation equation in a vacuum
is given by the tensor equation,

qF_uv,w + qF_vw,u + qF_wu,v =0

where F_uv etc. are the components of the Electric and
Magnetic fields, and the comma is the partial diff, and
q is electronic charge.

Any radiation emission or absorption would require the
charge q to be subject to a varying EM field given by the
components F_uv,w etc. that are relatively varying quantities.

Naturally, when all the EM field components (F_uv) are
zero or constant, no radiation can occur.
(questions on these equations, ask).

Actually it will radiate. When there is a relative acceleration of charge
and detector/observer, radation will be detected.
Pmb

Agreed
[snip]

Regards Ken S. Tucker

Can I ask what "relative acceleration" means? I thought in relativity that
accelerations were absolute.