Cecil,

I do not have a copy of Hecht, but I doubt that he has made any serious
mistakes. Certainly he should have no mistakes in an area that is as
well understand and widely discussed as plane wave interactions with
discontinuities in the medium.

The classic treatment of this problem, found in virtually every
college-level textbook on E&M or optics, is to set up the appropriate
wave equations, add the boundary conditions, and crank out the answer.

Then there is typically some sort of analysis and discussion that says,
"The reflected intensity plus the transmitted intensity is equal to the
incident intensity. Energy is conserved." I suspect Hecht provides
exactly that sort of description. I know that all of the relevant
textbooks I have do so.

I believe you are reading too much into something Hecht is saying,
perhaps in an effort to somehow reconcile conservation of energy.

The beauty of the laws of E&M, as expressed by Maxwell's equations and
other fundamental properties, is that conservation of energy is
automatic, at least in ordinary circumstances. If one correctly solves
for the field equations, the energy conservation will come along for free.

Conversely, it is customary to use energy considerations as the primary
vehicle for addressing many physical problems in advanced mechanics,
quantum mechanics, solid state physics, and other branches of science.

The bottom line is that there are a number of tools available to develop
correct solutions to physical problems. Steve Best chose one path, and
you choose another. You both come up with the same answer in terms of
what can be measured. The mathematical constructs underlying the
solution may be different, but those constructs are not directly measurable.

Don't limit your toolbox. Sometimes a screwdriver is easier to use than
a monkey wrench.

73,
Gene
W4SZ



Cecil Moore wrote:
Gene Fuller wrote:

I thought my intention was obvious, but it seems I failed to communicate.


Others on this newsgroup have admonished me for worrying about
energy and refused to discuss the subject. I thought you were
doing the same. Sorry. But do you actually have any references
that contradict "Optics", by Hecht?

In Dr. Best's article, he superposes V1 with V2 such that constructive
interference energy is needed to complete the superposition. On this
newsgroup, I asked Dr. Best where that necessary constructive interference
energy comes from and he didn't know. That's when I went searching for
references and found them in the field of optics.

Constructive interference energy can be supplied by local sources
as occurs in W7EL's "Food for Thought #1" with its DC example. Or
constructive interference energy can be supplied at a point away
from the source(s) by destructive interference, e.g. wave cancellation
at the non-reflection surface of a layer of thin-film on glass or
at a match point in a transmission line.