Simple question, or is it...


What exactly is an audio signal made of, and what exactly is the medium it travels through in a cable??
thecarpathian
I've been doing a lot of reading mainly here the link jea48 gave.

 http://amasci.com/elect/poynt/poynt.html
 
The great thing about this link is there are a whole lot of other articles besides the one on Poynting vectors. 
Two things are at play the charge flow in the wires which is very slow and forms a circuit. Measured in amperes which is "one Coulomb of charge flowing per second". So far so good.

Also there is Energy flow which flows between and around the wires measured in watts, a quantity of electrical energy flow per second. Energy is measured in Joules so 1 joule a second is 1 watt.

 What is electrical energy, it's made of electric fields and magnetic fields, Electromagnetism. These two things flow in a circuit at the same time. Charge flow in the wires very slow in a continuous circuit and energy flow outside the wires from the source to the load. 

We're left with one thing What are Joules?  Joules of Electric energy are made from Electromagnetism they are flying around between the source and load and are the same stuff as radio waves but in this case they ATTACH  themselves to the wire and FLOW along the columns of movable electrons in the wire, the charge flows in the wire slow, the energy flows outside the wire at almost the speed of light and the Joules flow in the electron columns carried with the energy. 
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OK, you convinced me. Waving the White Flag here, guys! 🏳 Going back to metal clothes hangers ASAP.
Why wave the white flag, you're right the Joules which are in the electromagnetic wave are in the wire. The wire carries the signal, the signal isn't the energy flow. At least that's the take I'm getting from all those links jea48 posted. Well other papers from the link. 
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