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Old August 30th 03, 12:33 PM
 
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W5DXP wrote:

wrote:
So are you saying that like charge does not repel?


No, I'm not saying that at all. In fact, there may not be any charges
crossing the NET voltage = zero point and there doesn't have to be for
energy to be flowing in both directions.


This does seem to be the sticking point, doesn't it. Starting with
p = v * i,
i = charge_moved/time,
if no charge moves, there can be no power, and from
p = work/time,
if there is no power, no work is being done,
and if no work is being done, no energy has moved.
Ergo, no energy crosses the boundary.

If you find an error in the above derivation, I will happily allow
you that energy flows in both directions.

Two waves flowing in opposite
directions in a constant Z0 environment superpose but have no effect
on each other. You are continuing to be confused by the NET values.


Actually, I am not confused by NET at all. I contend that NET is the
only thing of importance when determining if energy flows.

Did you take a look at that Java-driven web page that I posted a couple
of days ago. If so, I don't see how you could still be confused.


Are you referring to
http://www.mellesgriot.com/products/optics/oc_2_1.htm?

These dudes do seem to have it right. They sum amplitudes to get
the resultant (NET) amplitude and then compute the intensity (power)
from the resultant (NET) amplitude. They do NOT state that energy
flows across a point with zero resultant amplitude nor do they sum
the power (intensity) to determine interference patterns.

As an analogy, consider two equal magnitude Tsunami waves flowing in
opposite directions in the ocean. According to you, these waves will
reflect off of each other. But it is known that those two waves will
simply flow through each other and continue their original paths
unabated.


How can you tell whether it reflected, or flowed through?
The look and feel will be the same.

Remember the collision of two identical balls. Superficial examination
of the collision might cause one to conclude that the energy was
transferred between the balls, especially if you viewed this collision
after viewing the collision of a moving ball with a stationary one
where energy is indeed transferred. Only by looking at the details of
the collision, in particular at the interface where the collision
occurs,
and realizing that f * d is always 0 do you learn that no energy was
transferred.

Similarly for transmission lines at points where v(t) * i(t) is always
0 and, from the web page, apparently for light as well.

....Keith