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superconductors!

Name: lol i suck 2009-02-05 14:46

can you apply ohms law to superconductors?
V/I = 0? :S

Name: Anonymous 2009-02-05 15:16

Sure, why the hell not?

Name: 4tran 2009-02-05 15:31

V = 0 is a trivial statement.  You know nothing of I.

Name: lol i suck 2009-02-05 15:33

doesn't it imply that in the presence of a potential difference there is infinite current (even if only for a tiny amount of time?)

Name: Anonymous 2009-02-05 16:10

INFINITE CURRENT IS AN IMPOSSIBILITY.

Name: Anonymous 2009-02-05 16:31

>>1

Yes. It means that even if current is flowing there is no potential difference between one end and another of the superconductor. No voltage.

ΔV/(any I) = 0

Name: Anonymous 2009-02-05 17:19

I am very confused. Why would current arise without voltage? If you place it in an electric field wouldn't that force there to be a voltage? At least until its electrons arranged properly so there wasn't any more?

Name: Anonymous 2009-02-06 2:42

Ohm's law is based on a number of hypothesis that are only approximations.  Superconductors probably have little chance of actually verifying those.

Name: Anonymous 2009-02-07 11:43

>>7

That's just it. There is no electric field! At least, not within a superconductor. There is no law stating that current absolutely requires an electric field to be present.

Name: Anonymous 2009-02-10 18:10

>>9
| There is no electric field! At least, not within a superconductor.
WRONG,
in a semiconductor there is no resistance, there is still an electric field and surely there must be a current.

ps. Ohm's law doesn't apply to superconductors.

Name: 4tran 2009-02-10 18:19

>>10
Surely, you mean superconductor, and not semiconductor...

Superconductors behave quantum mechanically, which is why weird shit happens.

Name: Anonymous 2009-02-10 18:29

>>11
yes that's what I meant.
brain farts, etc.

Name: Anonymous 2009-02-15 20:23

>>10

There is no electric field! At least, not within a superconductor.

WRONG,
in a semiconductor there is no resistance, there is still an electric field and surely there must be a current.

That's not what my physics book says. Can you cite something that backs your claim up? I'm not trying to be argumentative here. Just curious.

Name: Anonymous 2009-02-15 22:06

\frac{\partial \mathbf{j}_s}{\partial t} = \frac{n_s e^2}{m}\mathbf{E}

http://en.wikipedia.org/wiki/London_equations

Name: Anonymous 2009-02-15 22:18

oops, hit post too soon.

For a constant current there is no electric field within the conductor, all charge moves along the surface. This is why high strength superconducting magnets are made from many tiny wires for greater surface area.

Name: Anonymous 2009-02-15 23:21

>>15

Awesome. Thank you.

Name: Anonymous 2009-02-16 1:40

So, this is a music thred?

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