Keith Dysart wrote:
On Jan 15, 2:24 am, Roy Lewallen wrote:
The little program I wrote shows that, on the line being analyzed, the
energy is changing -- moving -- on both sides of a point of zero power.
Energy is flowing into that point from both directions at equal rates,
then flowing out at equal rates. This causes the energy at that point to
increase and decrease. What zero power at a given point means is that
there is no *net* energy moving in either direction past that point.

"*net* energy moving" seems to be a bit of a dangerous notion.

If "*net* energy moving" is the time averaged power, then
it is zero at *every* point on the line under consideration.
And I do not mind this definition.

That was probably a bad choice of words on my part. By net I didn't mean
an average over some period of time. I meant energy moving past a single
point.

One possibility I envisioned was some energy moving past the point from
left to right, and at the same time an equal amount moving at the same
rate past the point from right to left, resulting in zero power at the
point. However, on reflection, this couldn't happen; energy flows
"downhill". But the phenomenon observed on the open circuited line does
occur, where energy flows into the point from both directions equally,
and out of the point to both directions equally, resulting in zero power
at the point. No energy is flowing past the point, period -- the
modifier "net" isn't necessary.

But at the points where the current or voltage is always
zero, it seems to me unnecessary to use the qualifier "*net*"
since the power IS always zero [from p(t)=v(t)*i(t)]. That
is, unless you are introducing another interpretation of
"*net*".

You're right. Please consider "net" retracted.

Roy Lewallen, W7EL