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Keith Dysart wrote:
The energy flow into the battery is exactly and always accounted for by the energy flow that heats the battery and the energy flow consumed in the reversable chemical reaction. Point is, energy can be stored and released at a later time. You earlier said that reactances do not store energy for release at a later time yet that is exactly what reactances do. A strange of way of looking at it. It seems easier just to say that there is no theta. And add the voltages. Saying there is no theta is a shortcut that can get one into trouble as it did with you. Since there is no such thing as negative energy, there is also no such thing as negative power. Note there are no negative power signs in the power density equation where 'theta' is the phase angle between the two interfering voltages: Ptot = P1 + P2 + 2*SQRT(P1*P2)cos(theta) The last term is known as the "interference term", page 388 of "Optics" by Hecht, 4th edition. When 90 theta 180, the sign of the last term is negative indicating destructive interference. When 0 = theta 90, the sign of the last term is positive indicating constructive interference. When theta = 90, there is zero interference which is what Part 1 of my web articles is based upon. This Pr.correction term has nothing to do with interference, ... Your argument is not with me but rather is with Eugene Hecht who defined that term as the "interference term" in "Optics". Have you even read his chapter on interference? If not, I would suggest that you do so. Two other enlightening chapters are on "Superposition" and "Coherency". Note that there is no hint that Pr.correction needs to be stored when it is negative nor come from somewhere when it is positive. You're correct, there's no hint. It is spelled out in detail in "Optics". The possibilities are listed below. Your above statement is a conceptual violation of the conservation of energy principle. In the absence of any other energy source or energy sink, localized destructive interference must exactly match the localized constructive interference magnitude in order to avoid a violation of the conservation of energy principle. This is why a Z0-match works. Since one needs to know the constituent voltages to determine the sign of Pr.correction, why not just use superposition to compute the total voltage and then derive the power? That is what has extended this discussion to arguments over the past quarter century. That 30,000 foot method says nothing about where the ExH energy in the reflected wave goes. The irradiance (power density) equation with its defined "interference term" tells us exactly where all the energy goes and answers the question: What happens to the ExH energy in the reflected wave? Here are the basic principles: When destructive interference occurs, there is "extra" energy left over from that isolated event. That energy must go somewhere. Here are the possibilities in a typical lossless RF transmitting system. 1. The source can throttle back on its energy output to compensate for the destructive interference energy. 2. Reactive components can store the destructive interference energy and return it to the network at a later time. 3. In the absence of (1) and (2) above, an RF energy wave is launched in a direction that allows the "extra" energy to leave the destructive event area. The last possibility is why we can observe reflected energy being redistributed back toward the load in the complete absence of single-wave reflections. When constructive interference occurs, there is "missing" energy needed to be supplied into that isolated event. That energy must come from somewhere. Here are the possibilities in a typical lossless RF transmitting system. 1. The source can simply supply the energy needed by the constructive interference event. 2. Reactive components can return stored energy to the network. 3. In the absence of (1) and (2) above, constructive interference energy *must* be supplied in real time by destructive interference between two other waves. ************************************************** ******* * The last possibility is how a Z0-match redistributes * * all of the reflected energy back toward the load when * * the physical reflection coefficient is not 1.0. * ************************************************** ******* The two-step process of redistributing 100% of the ExH reflected wave energy back toward the load is covered in my other energy analysis article on my web page at: http://www.w5dxp.com/energy.htm This analysis also makes clear the nature of powers computed from the constituent voltages of superposition. These powers do not represent real energy flows. As discussed far above, real energy flows can be summed to test for conservation of energy. Translation: Don't bother trying to ascertain where the ExH component wave energy goes. Since the conservation of energy principle cannot be violated in reality, it is OK to violate it conceptually. Now where have I heard that argument before? :-) "I personally don't have a compulsion to understand where this power 'goes'." Do you really think that the ExH energy in a reflection from a mirror does not represent real energy flow? -- 73, Cecil http://www.w5dxp.com |
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