Today I'll revisit the telegraphers' theory. It all seems so obvious nobody stops to ponder the particle (electron) dynamics of the telegraphers view of electricity and how it moves around. The equations were advanced by Heaviside and apply to power distribution as much or more as they apply to information signal distribution. This model applies to small traces on printed circuit boards as well as integrated circuits and long distance power transmission lines between cities.
A power or signal electrical transmission line can be modeled by series resistances measured in ohms per meter. In series with the resistance the telegraphers' model specifies an inductance. We shunt a capacitance and a conductance. Briefly, the resistance represents electrons resisting flow as they smash into the lattice of the transmission line. Inductance has classically been thought of the generation of a magnetic field by moving electrons. Capacitance between the transmission wire and the return stores energy in the electric field. Conductance is the flow of electrons between the transmission wire and the return. In the case of a differential signal both wires are transmission wires.
Resistance is the impedance to the flow of electrons through a wire. The electrons are accelerated by a classical electrical field. These electrons often travel at a fraction of the speed of light. At this high rate of speed the electrons often slam into a copper nucleus which has a mass ten thousand times higher than the offending electron. The vibration imparted to the copper nucleus causes heat in the copper lattice. The electrons accelerate each other through more interactions and the power of the electrons propagates down the wire.
Inductance may be the least well understood impedance ever. Inductance infers an induced magnetic field if you believe in magnetic fields. I'll submit that the induced field is simply (simply is a bad way to state it) a field of curling or spinning electrons. A certain statistical amount of all the electrons that are traveling down a wire each meter will eject themselves from the wire and spin out into the dielectric. The dielectric could be a polymer or simply the air. All of these dielectric substances contain molecules that the 'hot' electrons can orbit. The nature of these orbits has not been well characterized by physicists. It is most important to note that a certain percentage of electrons ejected from a wire each meter will orbit in the dielectric and end up right back on the wire creating the characteristic 'paddle wheel' or 'magnetic' energy storage effect.
Capacitance is another energy storage mechanism whereby electrons ejected from a wire will store energy. The build up of electrons in the dielectric region between the transmission wire and the return wire of any electrical system. Capacitance in Farads per meter represents the electrons that leave the transmission wire (and or return wire) but don't make their way toward the return wire in the case where they left the transmission wire. These electrons just hang out in the dielectric outside the transmitting or conducting zone.
Finally, conductance shows us that electrons are definitely ejected from 'hot' wires. These electrons make their way, statistically, to fill holes on the return wire assuming the transmission wire was negatively charged in the first place.
There are currently no good statistics showing what the path looks like for an electron that experiences the inductive spin, the capacitive hang or the conductive path form wire to wire. Capacitance and inductance involve an electron leaving one wire and landing back on that self same wire whilst resistance and conductance in the telegraphers' equations refer to an elongated path or a shortened path for electron travel in the case where the electromotive force has exerted itself on a group of electrons traveling over some sort of transmission line.
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