That's true, but light only travels at ~0.67c in a fibre optic cable. That's why I mentioned that fibre optic cables and copper wires are not vacuums.
Re:Why the NBN needs to go the full way
by retrogradeorbit on Friday September 06, 2013 @01:59AM
(#6338915)
According to wikipedia, electric field propagation through unshielded copper is 0.95c to 0.97c. Electric field propagation through standard coaxial cable is 0.66c.
Hence why zmmmmm was incorrect about the speeds: electricity in the copper wires is travelling faster than light in the fibre optic cables. zmmmmm didn't mention drift velocity, but that wasn't really related to his point.
Re:Why the NBN needs to go the full way
by Wingman4l7 on Friday September 06, 2013 @02:05AM
(#6338932)
Thanks for the refresher -- I recall being taught this in HS physics but I've never repeated it because I didn't want to look like an idiot trying to explain how "electrons" don't move at the speed of light.
But what happens when you close a circuit of a conductor across a potential difference is an electric field is set up surrounding the conductor. This electric field accelerates all the electrons in the conductor at once. This is why even though the drift velocity of an electron in a conductor is very low, when you switch on a light switch the bulb lights immediately.
The propagation of the electric field is at the speed of light (its electromagnetism). So "electrons" move slowly but "electricity" moves at the speed of light.
Update: found a wikipedia page on it: http://en.wikipedia.org/wiki/Speed_of_electricity