Tim Wescott wrote:
Cecil Moore wrote:

It has been said that the energy stored in the standing waves
of a transmission line just "sloshes" around.

We can demonstrate standing waves using a laser beam normal to
a perfect mirror. There are points of maximum irradiance and
points of minimum irradiance in the standing waves. So does
the EM energy in the standing waves of light in free space
"slosh" around like the energy in the standing waves in a
transmission line?


Yes -- there's energy actively bouncing around in that there beam; if
you could reduce it down to one laser burst that was shorter than the
distance between the laser and the mirror you'd (in theory at least) be
able to see it.

If so, where does the inductance and
capacitance in free space come from to generate that 377 ohms
of characteristic impedance?


They don't. The behavior of EM radiation in free space is described by
Maxwell's laws. The 377 ohms of characteristic impedance comes from the
permittivity and permiability of free space but inductance and
capacitance are only meaningful concepts if you have conductors in your
model.

If not, then why do the EM waves
in a transmission line behave differently than the EM waves
in free space?


Because they're bounded by conductors.

What different laws of physics do photonic waves
in transmission lines obey than do photonic waves in free
space?


None. They obey Maxwell's laws.

Of the E-field and H-fields rules for EM waves in free
space, which of those rules are violated by EM waves in a
transmission line?


None.

Is there one set of Maxwell's equations for
free space and a separate set for transmission lines?


No, just different boundary conditions to start.

All this is covered in a good college E&M course. I wish I had an E&M
book that I could recommend for self-study, but I don't. Mine is
"Elements of Engineering Electromagnetics", but I took a course. I
don't think I would have been able to just pick up the book and learn it
from there.

Did
Maxwell ever mention the scientific concept of "sloshing"?


Who knows? And was he talking about light waves or a wee dram of
whiskey at the end of the day?

As hard as it may be to believe for anyone who's gone through an E&M
course the original form of Maxwell's equations were more difficult to
comprehend than the way there're usually presented now -- the vector
notation that is currently used either wasn't around then or wasn't in
widespread use.

-------------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Hi Tim,
Cecil is just trying to crowd Roy into slapping leather
(figuratively speaking). Cecil thinks he already knows the
answer to all these questions, so there's no
point in answering him. He'll be at it for awhile, until he
realizes rhetorical confrontation won't work.
73,
Tom Donaly, KA6RUH