On Jun 26, 9:05*am, Cecil Moore wrote:
On Jun 25, 4:00*pm, Keith Dysart wrote:

That's the time domain. Variation in the instantaneous energy flow.

What you seem to be missing is that the *energy content* of power
(total joules) must be conserved but the instantaneous power (joules/
second) does not have to be conserved as you have argued numerous
times in numerous examples.

In any region, the energy flowing in (i.e. power) to the region minus
the energy flowing out (i.e. power) is equal to the additional energy
per unit time (i.e. power) being stored in the region. While not
called the "conservation of power law" it is an obvious corollary
to "conservation of energy".

The only question that needs to be
answered is: In a system designed to eliminate reflections and
interference, does all the reflected energy eventually get dissipated
in the source resistor. The answer is yes because there is nowhere
else for it to go.

The obvious alternative is that the computed energy in the reflected
wave is sometimes just a figment. Or is something else happening with
the step function example?

Not to mention that in your 1/8 wavelength example (http://
www.w5dxp.com/nointfr.htm)
you do not explain where the energy is stored so that it can be
returned at a different time.

There is no conservation of power principle and
that includes instantaneous power. So it is irrelevant what/where
instantaneous power might do/go during a single cycle.

Such declarations do permit an easy out, despite not aligning with
reality.

Now I understand that instantaneous power dictates some physical
design considerations as in waveguides. But since instantaneous power
does not fall under the conservation of energy principle, it is simply
irrelevant to the present discussion. What happens over a complete
cycle is what is relevant.

If that is the case, the whole concept of reflected energy seems
somewhat bogus. Over a whole cycle, the power delivered by the
generator is passed on towards the load. If that is all you want
to know, then there is no need at all for "reflected power".

However, in any and every case, it is energy that is conserved,
not power.

Yes. But see the related corollary above.

How many joules are in that dt
sliver of time when the instantaneous power is 100 watts? It's those
joules that must be conserved, not the instantaneous power.

Still having problems with mapping the concepts from calculus to the
real world, I see.

You didn't answer my previous question. If you measure 100 watts of
instantaneous power at 100 places within an inch of each other, does
that mean there is 10000 watts of instantaneous power in that one inch
of wire? That is the only logical conclusion based on your argument
and assertions.

No more than "If you measure 100 watts of *average* power at 100
places
within an inch of each other, does that mean there is 10000 watts of
*average* power in that one inch of wire?"

But it is a way of thinking that you like to use to distract
yourself from the really interesting results.

Any argument based on the conservation of power is
doomed to fail. Please get real.

Please study the corollary above.

Not quite
'as useless as tits on a boar hog, or as Hecht said, putting it
mildly: "of limited utility"'.

One could argue that tits on a boar hog are not completely useless
and, therefore, instantaneous energy is exactly as useless (or exactly
as useful) as tits on a boar hog. (Hint: Without the existence of the
tit gene in the male, female hogs would probably not have tits.)

So which is it? Is instantaneous energy flow a useful concept? Or is
it
not? You previously suggested an understanding of the value (when I
mentioned "real power folk"), but seem to continue to want to argue
its complete lack of usefulness.

And to stop besmirching Hecht, it seems most probable that his
comment was in the context of optics. After all, the book had that
title.

....Keith