W5DXP wrote:

Jim Kelley wrote:
Nodes and zero crossings aren't necessarily the same thing.

They are for standing waves on lossless unterminated lines,
by definition.

I think not. Standing waves are spatial. At certain points
on the line the (NET) voltage is always zero: nodes.
At other points on the line, the (NET) voltage is sinusoidal
and has 2 zero crossings per cycle. The amplitude of these
sinusoids varies spatially along the line resulting in the
standing wave.

In an ideal line terminated by Zo, no matter where you attach
your oscillograph to the line, you will observe a sinusoid
of the same amplitude. This sinusoid will have zero crossings
and power at the time of these zero crossings will be zero;
no energy will be flowing at the time of the zero crossing.

And going back to the comment that started this sub-thread,
it is this cyclical variation in energy flow which prompted
the power dudes to invent three phase lines in which the
energy flow does not vary cyclically; power is constant.

....Keith