Ask A Scientist General Science Archive

status       educator
age          40s

Question -   Admiral Grace Hopper once passed out wires of certain
length to demonstrate the average speed of an electron in a nanosecond.
What would this length be?
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She passed out roughly foot-long wires.  This is the distance light
would move in a nanosecond.  Electrons do not move at anything like that
speed in a wire.  Signals travel in a wire at something like 1/3 the
speed of light, depending on details of the wire's construction.

---Mooney
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Up-date December 2005
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The speed of a signal in a cable is 0.66-0.83 percent of 
the light speed. 2 feet in one nanosecond. Manufacturers of cable 
specify a velocity-factor for their cables, which is the ratio 
between 'real' speed in their cable and c. 

(http://www.nr6ca.org/vf.html gives you a small list)

Thanks to Ruben!
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