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On Oct 6, 12:45 pm, wrote:
Le Chaud Lapin wrote: On Oct 6, 6:38 am, Matt Whiting wrote: Really? Many books still can't agree on the definition of current. Some say it is the movement of electrons and some say it is the movement of positive charge and some say it us both. Which is the absolute truth, Mr. Wizard? The truth is that the electrons move, not the protons. You've fallen into the trap you are complaining about and providing a simplistic answer that isn't true under all circumstances. Uh...no. The difference, as I pointed out with great redunancy in my post, is that, in one case, there are two situations: 1. The truth, which the observers know. 2. The untruth, which the obsevers concoct to make the math simpler, all the while keeping in mind what the truth is. This is what happens with semiconductors. In the other case, there is only one situation: 1. What the observers think is the truth. In this latter case in aerodynamics, the observers do not say, "We all know that this is not what is really happening..". Instead, they say, "This is what's happening." I can think of no mechanism to move protons in a solid, but they move quite well in a vacuum. Yes, I know. When I was tutoring electrodynamics, I used the problem that I am sure you are familiar with, a proton, entering a uniform magnetic field, and one must find the radius of its circular motion based on the mass of the proton, the magnetic field intensity, etc. This problem is so common, I decided to use a proton instead of an electron to try to catch students who were cheating by simply copying problems from previous years. The answer given by cheaters would have the right radius but the wrong direction. Ever heard of a proton accelerator? Yes, in fact, I had it as a disclaimer in my original post, just as I had a disclaimer about a capacitor not being negative. [Note I said that capacitors have positive capacitance, which is true, until you start implementing virtual capacitors using general impedance converters, which can make them negative, but then they are not real capacitors, etc.] I took out counterexample about proton accelerators because Wikipedia did not have an immediate link for the exact phrase "proton accelerator", and the related links were bordering on quantum physics, and I certainly don't want to open up a can of worms about quantum physics in this group. A current flow in a proton accelerator is a current flow of protons. Sure. But no one ever disputed that. Matt was implying that electrical engineers/physicist cannot agree on what is actually going on, which is not true. Most physicists who work with proton accelerators are quite aware that that there is a proton moving under the influence of the Lorentz force in an accelerator. No particle physicist ever claims otherwise. Also, if you ask a bunch of electrical engineers, "Does everyone that every know that there really is no such thing as a hole, that it is in fact massive numbers of protons, entering an exiting the energy band according to a stochastic model?" They would say, "Yes, yes, we know! Now get on with your talk about these non- existent holes." Aerodynamics, today, is different. If you ask a bunch of aeronautical engineers, "Does everyone know that the lift is due to the air on top traveling faster than the air beneath, thus invoking Bernoulli's Principle..yada yada....", Barry Schiff, and the person who wrote the article at NASA, will say, "No. We do not agree with what you just said." -Le Chaud Lapin- |
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