[sdiy] Speed of electrons? (was mass extinction of the dinosaurs)

[Magnus Danielson]

From: KA4HJH <ka4hjh at gte.net>
Subject: Re: [sdiy] Speed of electrons? (was mass extinction of the dinosaurs)
Date: Tue, 24 Jul 2001 04:13:48 -0400

> Magnus:
> >Now, this seems like a little mess here...
> 
> I realize that it's not that simple. The reason I asked is because most
> people just assume that electricity moves at the speed of light "or
> something". I was just curious about what's happening at the more or less
> macroscopic level in the sort of electronic gadgets we're talking about
> here. Not that I mind hearing the details...

The change in current and potential difference moves at the speed of
light, but this speed changes with the material and physical
layouts. It effectively depends on the stray capacitances and stray
inductance among other things. A "perfect" modelling is a major
headache, but rougth estimates can make you come into the
neighborhood.

What the semiconductor people is trying to do is to make better and
better estimates by automatic means on a fair amount of calculation.

> matti :
> >Fibreoptics.
> 
> Well, even then you won't achieve the speed of light because of the density
> of the glass, among other things. But it certainly would be faster.

Actually, it moves the speed of light, it's just that the speed of
light has been lowered! It is however true that it is not at the
speed of ligth in vacuum, but that is another thing. What did we learn
by that? Sloppy usage of terms helps to confuse. We think we know the
meaning, but when we start to analyse we learn we used the wrong wording.

> John L Marshall:
> >PC computer front side buses are now running at 400 MHz. That is blazing
> >saddles, man.
> 
> It amazes me that this stuff works at all. Thanks for the info everybody.
> If your PC board starts glowing blue your electrons are moving too fast,
> and it ain't from the heat...

Hehehe... at work I see 2.5 GHz signals on the PCBs and I expect yeat
higher speeds to come. Interestingly enougth, some of the knowledge I
have gathered by working with audio needed just a thad of update to
understand the situations here.

I guess soon enougth I'll find myself in the plumbing buissness.

Cheers,
Magnus