Radar:
electrons move in a particular direction (towards the positive) for only 1/120th of a second, then they reverse direction (because the positive has moved) for another 1/120th of a second. How far they move in that time? Who knows? Probably not very far.
Not very far, indeed! I was
astonished to find out just how slowly electrons travel in copper wire. It's:
(4.62 millimeters/second) per (volt per meter).
So, what the heck does that mean?
It means that if you take a piece of wire one meter long and connect a one-volt battery across the ends, the electrons travel at the rate of 4.62 millimeters (less than 3/16") per second!
If that doesn't sound like a lot of work getting done, consider that if our one-meter wire is awg-24 (0.5 mm), the current is over 12 amps!
The diameter of the wire doesn't matter. As the wire gets larger, the current goes up proportionally, but the velocity stays the same.
If, instead of a one-volt battery, we apply one volt RMS, 60 Hz AC, that Sharpie-marked electron travels only 1.4 thousandths of an inch in each direction.
Sort of...
Actually, a more correct term for electron travel is "drift," rather than velocity. Electrons are constantly zipping around at 1.3 million meters per second, the Fermi velocity, even at absolute zero. They're just moving in random directions, so there's no net current without an electromotive force applied.
Is that cool, or what?
