Re:

[Chuck Britton <britton@odie.ncssm.edu>]

William Beaty wrote
                            [MAJOR snip]

> So, rather than using a 100KM copper rod, I use a pair of parallel 100KM
> copper rods, with the ends joined at both distant end locations.  I want
> to push the electron sea, so I stick a motor at one end of the rods, and a
> generator at the other.  Now, if I suddenly start cranking the motor, I
> push electrons into one rod and suck them from the other.  A wave of
> "work", of compression and motion, starts at my end, travels along the
> rods, and ends up at the far end, where it moves the generator.  Does the
> wave of "work"  move at the speed of light?  I don't know.  Electrons have
> nonzero mass, so I would think that it moves a bit slower than c.
> Regardless, I'd better make my rods a million KM long, so that it takes a
> few seconds for my "work" done on the generator shaft to appear on the
> distant motor shaft. 

The electrons themselves will move surprisingly slowly. A few mm/s for 
several amps in common lab sized wires! But the electromagnetic 
disturbance will move at a speed comparable to that of light. The 
specific responce time will depend on the inductance and capacitance of 
the 'loop'.
In this case the wave of 'work' is probably sometime refered to as a 
'voltage' pulse. (I might be tempted to define voltage as Work/charge but 
somebody might take umbrage.)