Home |
Search |
Today's Posts |
#11
![]() |
|||
|
|||
![]()
On Jun 29, 9:46*am, Cecil Moore wrote:
On Jun 28, 5:27*pm, Keith Dysart wrote: And yet, you have not located any errors in the math or the models. Superposition of power *IS* an error! You have really latched on to that haven't you. I remember the good ol' days when you were superposing powers and the very same people with whom you are arguing today were trying to convince you that superposing power was an invalid operation. Now you have bought in to the rule and apply it even where it does not apply. Just because a sum is being computed does not mean that superposition is at work. When you add up the energies to validate that energy is not created or destroyed, you are not superposing energy. When I add up the energy flows for the same purpose, that does not mean that superposition is at work. From a basic calculus, if the energy balances, so must the energy flow: f(t), g(t), etc. are functions that describes the energy in individual entities of a system with respect to time. Then f(t) + g(t) + h(t) = k is the expression that says the sum of all the energies must be a constant, for energy is neither created nor destroyed. From basic calculus d(f(t) + g(t) + h(t))/dt = d(k)/dt d(f(t) + g(t) + h(t))/dt = 0 d(f(t))/dt + d(g(t))/dt + d(h(t))/dt = 0 d(f(t))/dt is the derivitive with respect to time of the energy (i.e. energy flow, or power) for the entity. So it is completely valid to sum these energy flows to track the energy within the system; as my example does. You add and subtract powers willy-nilly as if that mathematical step were valid which it is not. Two coherent 50w waves do not add up to a 100w wave, even using average powers, except for the special case of zero interference where the waves are 90 degrees out of phase with each other. True. You must always use the actual energy flows in the entity and not the powers that are not real. In order to use power as an energy tracking tool, we must be very careful to ensure that there is a one-to-one correspondence between energy and power, i.e. every joule passing a point in one second must result in one watt of power (no VARs allowed). Also true. And as is done in my example. If that one-to-one correspondence doesn't exist, no valid conclusion can be drawn from tracking the power and any valid conclusion must be based on tracking the energy which is no small task. The key is that there is no such thing as imaginary energy. All energy is real. Some "power" is not real. Agreed. Especially the power in the waves that are being superposed. That is why you need a fudge factor when you sum your partial powers from your waves. I carefully do not sum partial powers from superposed waves. A one-to-one correspondence does not exist in a standing wave. Therefore, tracking power as if it were equivalent to energy in standing waves is invalid. You have made that error for years. Please provide an example of such an error, preferably from one of my expositions. One-to-one correspondence also does not exist over a fraction of a wave. Of course it does. Energy must always balance; not just at the end of the cycle. Therefore, instantaneous power is irrevelent in tracking the energy. That's your latest error which is the same conceptual error as before. In general, average power in the traveling waves over at least one complete cycle (or over many cycles) has a one-to-one correspondence to the average energy in the traveling waves. But that one-to-one correspondence is more often than not violated within a fraction of each cycle. Now you are allowing us to create and destroy energy as long as it balances at the end of the cycle? Are you sure you want to do this? It does not align with the well understood principle of conservation of energy. If I follow that rule, I just make the cycle long enough, say, my lifetime, and I am golden. But I do not hold out any hope for this. Here's a quote from "Optics", by Hecht, concerning power density (irradiance). "If however, the 'T' is now divided out, a highly practical quantity results, one that corresponds to the average energy per unit area per unit time, namely 'I'." - where 'I' is the irradiance (*AVERAGE* power density). There you go again, assuming that the 'practical' challenges of optics also apply to transmission lines. On a transmission line, we can measure the voltage and the current. We do not suffer from the same constraints as optics. Use the tools that are available for transmission lines. Don't tie two hands behind your back just because those tools do not work in the optical domain. ....Keith |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Reflected Energy | Antenna | |||
Reflected power ? | Antenna |