RIP: Betty Holberton

From: Eric J. Korpela <korpela_at_ssl.berkeley.edu>
Date: Wed Dec 12 17:09:38 2001

> I was always of the impression that the electrons themselves move slower,
> but the propogation of waves in the magnetic field of a stream of moving
> electrons was 2/3 the speed of light (roughly)?

The actual propogation velocity depends upon the geometry of the situation.
In some situations (like in coaxial cable, a well analyzed PC board, a well
modeled chip) the propogation velocity can be well determined. In a random
wire among a tangle of others you take your chances. 1/3-2/3c is usual.
Lower and higher velocities are possible.

Electrons are very much (billions of times) slower. Calculating the average
speed of an electron is easy and is left as an excercise for the reader, as
is explaining why, for a given current, electrons in a resistor generally
travel faster than electrons in a wire.

Eric
Received on Wed Dec 12 2001 - 17:09:38 GMT