Re: Catt anomaly?

[Savinainen Antti <antti.savinainen@KUOPIO.FI>]

Hello,

I carelessly quoted

> > when a pulse is sent down a simple cable (e.g. coaxial),
> > the edge of the electric field is moving at c.

John Denker responded (as well as Bernard  Cleyet) to this. Of course I should
have clarified that c refers to speed of light in a given medium (or nearly so)
which is not the same as speed of light in vacuum.

What is interesting to me is that according to Catt two experts in
electromagnetism gave different answers to his question. Catt writes
(<http://www.electromagnetism.demon.co.uk/w99anbk2.htm>):

"Consider the case when the battery and lamp are connected by two very long
parallel wires, their length being 300,000 kilometres. When the switch is
closed, current will
flow immediately into the front end of the wires, but the lamp will not light
for the first second. A wave front travels forward between the wires at the
speed of light,
reaching the lamp after one second. This wave front comprises electric current,
magnetic field, electric charge and electric field. Negative charge appears on
the surface
of the bottom wire. All of this is agreed by all experts.

The question asked by the Catt Anomaly is where this charge on the bottom
conductor comes from, and the answers given to this elementary question are
contradictory, with the academic establishment split down the middle. Half of
the academics, led by McEwan, say that the charge comes from the battery to the
west and
reaches its proper place along the bottom conductor without having to travel at
the speed of light. The other half of the academics, led by Pepper, say that it
is
impossible for the charge to come from the west because it would have to travel
at the speed of light, resulting in the charge having infinite mass. Pepper
says that at the
moment when charge is needed to help the wave front along, it comes to the
surface of the wire from inside the wire, travelling at right angles to the
direction of the
wave front."

I guess that a surface charge theory (see for instance Chabay & Sherwood in
<http://cil.andrew.cmu.edu/rchabay_extra/mi_docs.html>) can account very fast
(but not c in vacuum) propagation of electric field in a conductor. But how?

Regards,

Antti Savinainen
Physics Teacher
Kuopion Lyseo High School/IB
Finland

Homepage: <http://personal.inet.fi/tiede/physics/>