Re: AC electricity

["John S. Denker" <jsd@MONMOUTH.COM>]

At 04:53 PM 1/17/01 -0800, Bernard G. Cleyet & Nancy Ann Seese wrote:
> But still puzzled.  True the field supplies the energy, but how does it do
> this? (rhetorical), but by moving e's.  The electrons' fields move more
> electrons, and so forth.

Good question.  If you think only of the _potential_ that electrons provide
for other electrons, you will never understand how electricity can be made
to flow around a _circuit_.  It's like trying to understand the Escher
waterfall
  http://www.worldofescher.com/jpgs/Waterfall.jpg
wherein the water flows around in a circuit, everywhere descending under
the influence of a potential.  Obviously there's something desperately
wrong with this picture.

In the case of real-world power companies, they do it by subjecting some
electrons to the non-potential voltage induced by a changing magnetic field.

It's not easy to draw a picture of a non-potential voltage, and it's not
easy to analogize it to fluids or pinball machines -- but nobody said that
all physics had to have simple mechanical analogies.

> Question? and how fast do the e's move in a vacuum,

What vacuum?  In most vacuums, there are no electrons, which makes the
question a bit hard to answer.

> a super conductor?

Well that depends on how much current you want to shove through it.
Obviously you can make the current (and the velocity) as small as you want,
so let's ask what the _maximum_ velocity is.

If you ask google about "high critical current" you can find reports of
people achieving over a million amps per square cm.  Ten thousand A/cm
would be more typical in ordinary applications.  Next, take a guess at how
many electrons per cm^3 are involved in the current;  one electron per atom
would be a good guess.  From that you can pretty easily figure out the
velocity.  It's not very fast.