In rec.audio.pro, Chris Hornbeck
wrote:
On Thu, 30 Oct 2003 22:09:17 +0000 (UTC), (Jay
Kadis) wrote:
At the velocity electrons travel in metal (nearly 186,000 miles/sec or almost a
trillion (10^9) feet/sec), that length difference wouldn't matter.
This looks to be the first error in the thread so far... the power
of 10 is correct, but it's called (at least in the USA) a billion - a
trillion would be 10^12. Or is a trillion actually 10^9 "over there?"
I know many of these words change meaning by three orders of magnitude
when they cross The Pond. I recall a "billiard" but I forget where it
goes in the sequence.
Strangely enough, electrons themselves only travel about as fast
as a person can walk.
Does anyone know how this was determined? I've always been
fascinated at how these things are discovered, like how the electron
(or 'quantum of') charge was determined with tiny charged oil drops
under a microscope.
A signal / impulse travels essentially in the
insulators of a cable, typically at about .7C.
At least, this is the number that several knowledgable folk on
this board accept for typical cables. In a recent thread, I
dredged a number of .1C out of ancient memory, and was soon
disabused of the idea.
There's also something called drift velocity, but I've not
seen it translated down to my level of understanding.
In this case the 'water pipe' analogy of electricity flow works
well. When you turn the valve to make water flow (into, let's say, a
hose already full of water but at low pressure), the pressure increase
travels at the speed of sound through water (which is I forget, but a
few times faster than it is in air), but the actual water only travels
a few feet per second.
Curiouser and curiouser...
Chris Hornbeck
new email address