But in fact it doesn’t answer the question posed by the OP. Otherwise it’s fine. He might as well say the sky is blue.
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??
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The E and M fields that are the Poynting vectors are just that - fields. Electric field and magnetic field. Not to be confused with electromagnetic waves. Fields are stationary. EM Waves travel at near lightspeed in a medium. So, if I’m not mistaken and I don’t think I am, that means the EM wave travels INSIDE the conductor. The E and M fields lie outside the conductor. They are stationary all along the length of the cable or wire. That explains why the type of metal, the purity of the metal and the physical non-symmetries of the metal influence the sound. |
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Electric charge moves together with electromagnetic wave at fraction of the speed of light in vacuum, dependent on dielectric (60-70%). What moves slowly in the wire is electron (drift velocity) - practically standing still at the audio frequencies. Electron doesn't have to be a carrier of electric charge - in water it is the ion. Electric and magnetic fields are constantly changing with alternating current, but energy is delivered on the outside of the wires from source to load (for AC and DC). The unit of Poynting Vector is "watts per square meter". Picture with battery and resistor illustrates this: https://en.wikipedia.org/wiki/Poynting_vector |
- 153 posts total