Cecil Moore wrote:
Keith Dysart wrote:
Superposition of voltages and currents seems to be quite
accepted and is an excellent tool for circuit and transmission
line analysis.

Do you really expect us to believe that those voltages
and currents can exist without energy? Maybe an example
of EM voltage and EM current existing without ExB joules/sec
would help.

Cecil,

If you actually understood the way the Poynting Theorem works, you would
not waste your time worrying about ExB. It provides no useful
information in support of your wacky energy flow ideas.


Hint: Although the Poynting vector is defined as ExB, this is only a
flux. If you are interested in information relating to conservation of
energy it is necessary to integrate over a closed volume. The total
integral of the flux over the surface of that volume is then equal to
the rate of change of energy within the volume.

In your favorite example, where energy is coursing back and forth along
the two directions of a lossless transmission line, this integral over
any volume you choose will be exactly zero. Even if you could separate
the forward and reverse waves the Poynting vector energy calculation
would still come out to exactly zero for each component as well as the
sum of the components. The same amount of energy exits the integration
volume as enters it. Only in the case where there is a source or where
there is loss will the Poynting energy calculation yield a non-zero value.

If you want further information you can check advanced textbooks such as
"Classical Electrodynamics" by Jackson or "Principles of Optics" by Born
and Wolf. I am sure there are many other references, but those are the
two I check almost daily.

73,
Gene
W4SZ