On Tue, 15 Jan 2008 14:18:15 -0800
Roy Lewallen wrote:

Roger Sparks wrote:

I can see why you find "no power" at the zero voltage point, but does that imply that there is no energy flow and no power from every perspective? As I write, I am struggling how to clearly differentiate between "power" as "work done" and energy as "capacity to do work", and what "network" are we defining.

Power at a particular point on the line is the rate of energy flow past
that point. It does no imply that any work is done anywhere, since any
energy flowing past the point can be stored. That is, in fact, exactly
what happens with the open circuited line in my analyses and illustrated
with TLVis1. You can see from the TLVis1 demo 4 that power is present at
all times and places along the line except a few select points. No work
is being done; energy is simply moving back and forth along the line and
between the E and H fields.

Are you objecting to my link between power and work?

I can understand how we might think of a moving voltage wave (on a transmision line) somewhat like a battery that moves along a straight line. With that view, there would be no power acting on the line, no work, and there would be no evidence of current.

If a capacitor discharges, work is done on the circuit receiving the discharge. It takes work to charge a capacitor. Are you thinking that on a continuous capacitor like a transmission line the energy just "slides" along (like a train on tracks) without change of energy, like a battery moving along?

In my view, logic demands a smooth flow of power and energy from source to load. We should be able to account for both energy and power for every instant of time, over every inch of distance. I thought you were doing that in TLVis1 demo 4.


. . .

I personally define power as a state/condition where "work 'is being' done", . Power must act over time and have a physical movement component. Voltage by itself does not fulfill this definition because no movement is observed. Current is movement, voltage is only an indication of where a concentration of charges is found.

Of course you're free to define anything in any way you choose. But
you've chosen a definition that's different from the one accepted in all
of electrical circuit analysis and all textbooks. So you can expect to
have a good deal of difficulty communicating with people who are
acquainted with the universally understood definition and assume that's
what you mean, rather than your own personal definition. To them, power
is the time rate of energy flow, dE/dt, period.

Are you again objecting to my link between power and work?

This definition sounds consistant with power flowing on the transmission line. We seem to fulfill the power definition of energy flow on a transmission line but you make the statement "No work is being done". Would you object to my example of requiring work to charge a capacitor?


. . .

Roy Lewallen, W7EL

73, Roger, W7WKB