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RE: Your theory doesn't hold water.

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In Reply to: RE: Your theory doesn't hold water. posted by jea48 on March 11, 2014 at 15:55:20

What I mean is, we transmit signals through wires and if we measure how long it takes from the time a signal goes into one end and comes out the other, one has a �propagation velocity� of that cable.

To picture the situation, imagine you had a pipe full of marbles form one end to the other. You force an additional marble in one end and nearly instantly, a marble is displaced at the other.
You can repeat this long enough until your first marble exits the far end if you want, but �that� time is not the propagation velocity of a signal.

http://en.wikipedia.org/wiki/Velocity_factor
http://www.picwire.com/technical/velocity_factor.php

Follow Ups:

RE: Your theory doesn't hold water. - jea48 22:23:21 03/15/14 (1)
The phrase "flow of electricity" refers generally to the movement of electrons (or other charge carriers) through a conductor in the presence of potential and an electric field. The "speed" of this flow has multiple meanings. In everyday electronics, the signals or energy travel quickly, as electromagnetic waves, while the electrons themselves move slowly.

This is what I have been trying to understand.
Would you agree, an audio signal traveling down a wire is energy in the form of an electromagnetic wave. The electromagnetic wave moves at near the speed of light. The electrons are basically just wiggling back and forth. (In an IC or speaker cable. No DC component in the audio signal.)

Do you agree or disagree?
- http://en.wikipedia.org/wiki/Speed_of_electricity (Open in New Window)
- RE: Your theory doesn't hold water. - Tony Lauck 08:44:10 03/16/14 (0)
  When it comes to the speed of signal propagation the movement of individual electrons is irrelevant, as every electron is identical to every other electron. Even the existence of electrons is irrelevant to this discussion. (The presence of individual electrons does matter when considering thermal noise, but that's a different discussion.)
  
  There is no need to go too far down the rabbit hole. It is necessary to stop at some point if one wants to accomplish anything. There are different levels at which subjects can be discussed, according, for example, to the knowledge and intelligence of the participants. This accounts for various explanatory scenarios that sometimes appear to conflict. In trying to get into a new technical subject, I have found it helpful to explore a range of books until I can find one that is at the right level to give me an effective learning experience, neither too difficult (incomprehensible) or too simplified (inaccurate and/or boring). Sometimes I have found it necessary to read through several levels of books before I could understand current research papers and sometimes I have given up the effort as too difficult for my talents and available time.
  
  Tony Lauck
  
  "Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

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