Its interesting … the debate which seems to happening around the various forums stimulated by this article, seems to be about how energy is propagated in a conductor.
Most textbooks say that moving electrons in connecting wires, carry energy around a circuit. It seems that the Poynting flux, the magnitude of which they've deduced from these measurements, is what delivers the energy. The drift current in a conductor is too slow for the the energy to be propagated by moving electrons.
Here's a paper by Ian Sefton of Sydney Uni.
He says …
Quote:
If you know the density of electrons (the number of conduction electrons per volume of wire), the diameter of the wire and a typical current you can work out how fast the electron sea moves along.
In a typical example of a 1mm copper wire carrying a current of 100 mA the answer turns out to be about 0.01 mm.s-1 which is much slower than a tortoise. If those electrons were picking up energy from the battery and then carrying it all the way to the light globe, you would have to wait an awfully long time to see the globe light up.
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Interesting ..
Cheers