You said:
You can see in the movie how an ac signal generates waves in a predictable pattern along the conductor. With the complex waves being generated by an audio signal going through a wire, those waves are going to, in turn, have an impact on the signal passing through the wire. That “feedback loop”, is going to change the signal. Not measurable I suspect because we are not yet measuring the right parts of the signal.The ac signal does not pass through the wire. The ac signal energy travels in the spaces between the wires in the form of an EM Wave.
Ralph Morrison:
The laws I want to talk about are the basic laws of electricity. I’m not
referring to circuit theory laws as described by Kirchhoff or Ohm but the
laws governing the electric and magnetic fields. These fields are
fundamental to all electrical activity whether the phenomenon is lightning,
electrostatic display, radar, antennas, sunlight, and power generation,
analog or digital circuitry.
These laws are often called Maxwell’s equations. Light energy can be
directed by lenses, radar energy can be directed by waveguides and the
energy and power frequencies can be directed by conductors. Thus we direct energy
flow at different frequencies by using different materials.
For utility power the energy travels in the space between the conductors not
in the conductors. In digital circuits the signal and energy travel in the
spaces between the traces or between the traces and the conducting surfaces.
Buildings have halls and walls. People move in the halls not the walls.
Circuits have traces and spaces, signals and energy moves in the spaces not
the traces.
Ralf Morrison:
Storing or moving energy.https://www.electronics-related.com/showarticle/1165.php
There is a common misconception that signals are carried in conductors. Somehow this association crosses over to the idea that conductors carry both signals and energy. A few simple calculations can show that this is a false idea. Consider a 50-ohm transmission line carrying a 5-volt logic signal. The initial current at switch closure is 500 mA. A typical trace is a a gram-mole of copper that has 6 x 1023 copper atoms (Avogadro’s number). Each atom can contribute one electron to current flow. Knowing the charge on an electron makes it easy to show that the average electron velocity for 500 mA is a few centimeters per second. What is even more interesting is that only a trillion electrons are involved in this current flow. This means that only one electron in a trillion carries the current. This also says that the magnetic field that moves energy is not located in the conductors. The only explanation that makes sense is that energy in the magnetic field must be located in the space between two conductors.Conductors end up directing energy flow - not carrying the energy.
poynting Vector
https://en.wikipedia.org/wiki/Poynting_vector
Here is a video for you to watch. The guy does a good job explaining the E (Electric Field), B (Magnetic Field), Poynting vector, and the electromagnetic wave.
Audio signals would be to the far left of the spectrum.
https://www.khanacademy.org/science/physics/light-waves/introduction-to-light-waves/v/electromagneti...
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