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Old January 17th 08, 01:06 PM posted to rec.radio.amateur.antenna
Keith Dysart[_2_] Keith Dysart[_2_] is offline
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First recorded activity by RadioBanter: May 2007
Posts: 492
Default Standing morphing to travelling waves, and other stupid notions

On Jan 17, 2:07*am, Ian White GM3SEK wrote:
Keith Dysart wrote:
So you seem to be claiming that the following two statements can be
simultaneously true:


1. Power [recall p(t)=v(t)*i(t)] is the rate at
* which energy is transferred.
2. Energy can be transferred when the power is zero.


To my simple intellect, one of these statements must be false.


The second statement is an oversimplification - it switches between two
inconsistent sets of boundaries. Energy is being transferred within the
system as a whole, even though the power p(t) at some individual points
within the system is zero. If you look consistently at the system as a
whole, there are no contradictions.


Expanding on statement 1) from above....
p(t) = v(t) * i(t)
computes the power moving between two networks
separated by the point at which v and i are
measured.

Expanding on statement 2...
Cecil's claim is that the "energy in" the
forward and reflected waves travel from end
to end on the transmission line.

Applying statement 1) to any point on an open
circuited transmission line where the current
or voltage is always 0 will yield a power that
is always 0.

Applying statement 2) to this same point yields
that energy is crossing this point.

This seems to me to be a definite contradiction
between 1) and 2) for the specific situation under
consideration.

...Keith