sci.physics.electromag

Szczepan Bialek wrote:
> "a_plutonium" wrote
> news:e8307014-0707-48b2-8498-7db91903e8ab@e6g2000prf.googlegroups.com...
> >
> > But, in the course of doing the
> > Maxwell Equations, we end up with
> > a altogether new and different current called the Displacement
> > Current.
>
> Maxwell Equations are for incompressible electric fluid (hydraulic analogy).
> I prefer the gas analogy (no the displacement current).
> >
> > If you are a physicist, have you ever wondered why superconductivity
> > is only with DC current, never AC?
>
> In a textbook is that there no resistance up to 10^8 Hz. Are you sure.

http://en.wikipedia.org/wiki/Superconductor calls it Zero electrical
DC resistance

But then again Tinkham in "Introduction to Superconductivity" 1996 on
page 39 uses
ideal DC and then talks about AC current density J in a dissipation
from superconduction
to normal conduction.

In the book "Superconductivity" Ginzburg & Andryushin, 2004, on page
29 speaks of
the Critical Current and talks of two types of current (1) eddy
screening current and
(2) transport current. Now whether AC is a transport current is
questionable.

From what little information I have gathered about superconducting
trains is that it is
superconducting magnets to elevate the train and then they are pushed
along the track
by another force. So can those trains be both DC and AC is
questionable.

As far as I know, the superconduction state occurs only in DC current.

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom
where dots of the electron-dot-cloud are galaxies