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On Mar 11, 7:18*pm, Cecil Moore wrote:
Keith Dysart wrote: So as yet, there is no mechanism to explain storage of reflected power so it can be dissipated at a different time in the source resistor. Of course there is, Keith. That's what reactances do. A reactance stores energy during part of the cycle and gives it back during a different part of the cycle. The energy stored during part of the cycle is the destructive interference energy that you are missing from you equation. It is delivered back during the next part of the cycle and dissipated 90 degrees later. When the signs of the two superposed voltages are opposite, there is "excess" energy available which is stored in the transmission line. 90 degrees later, when the voltages have the same sign thus requiring constructive interference energy, that "excess" energy is delivered back to the source resistor to be dissipated. Since we already know that the interference energy averages out to zero, the energy imbalance that you discovered is obviously energy being displaced in time by the reactance whether it is from a coil or from the transmission line. I can see that words describe a somewhat plausable conjecture, but to be convincing, a mathematical exposition is needed. When is the energy stored where? Energy stored in a capacitor, for example, should correlate with the voltage on the capacitor. Similarly for current in an inductor. To be convincing, the various functions of time need to align appropriately. So far, the only convincing expressions I have seen a Ps(t) = Prs(t) + Pg(t) and Pg(t) = Pf.g(t) + Pr.g(t) and, of course, all the corresponding voltage and current functions line up as expected. To show that the reflected power is dissipated in the resistor will require the derivation of some X(t) such that Prs(t) = 50cos(2wt) + Pr.g(t) + X(t) and X(t) needs to be in terms of some known physical quantities of the circuit. ...Keith |
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