scott wrote:

> I really don't see the problem.  Do you understand what happens if you 
> short a battery with a wire?  You will get a huge current flowing even 
> though the voltage across the wire is virtually zero.

How the hell do you figure that?

Surely the potential at one end of the wire is +4.5 V, in the middle 
it's 0 V, and at the other end it's -4.5 V, and therefore the potential 
*difference* across it is 9 V. How is that zero?

> If you put a 
> super-conductor across the terminals of a battery, would you expect a 
> current to still flow? After all, the voltage across the superconductor 
> would be zero...

Where would you measure the difference? You need two points.

Anyway, presumably a superconducting magnet is bizare enough that Ohm's 
law doesn't apply. (Hmm, I = V/R where R = 0. Yeah, that looks pretty 
undefined to... oh, wait, you're that guy who things that division by 
zero is defined, aren't you?)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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