Current in superconductors when a voltage is applied.

1. Feb 26, 2013

JackA7X

Suppose you a have superconducting loop connected to a 9V battery. What is the current through it? With a resistance of 0Ω, $V = IR$ gives ∞. I don't think that can be right... If it were, $V=\frac{I}{nAe}$ would give an infinite velocity... Does that equation even apply to superconductors?

2. Feb 26, 2013

marcusl

Current will be limited by the internal resistance of the battery. This happens for all batteries connected to low impedance loads.

3. Feb 26, 2013

JackA7X

So if we assume the internal resistance is 1.5Ω how do you calculate the current through the superconductor?

4. Feb 26, 2013

marcusl

I=V/R, just like always. In this case, 9A since a superconductor has 0 resistance.

5. Feb 27, 2013

syhprum

Marcus
There seems to be an arithmetical error here.

6. Feb 27, 2013

DrDu

Superconductors can only carry currents lower than a critical current value. If the current rises above that limit, they become normal conducting.

7. Feb 27, 2013

marcusl

Quite so, I hit the wrong key on my Blackberry. 6A.

8. Feb 27, 2013

JackA7X

Thank you, very helpful.

9. Feb 27, 2013

sophiecentaur

This is a "irresistible force and immovable object" type of question, if you don't allow something to be non-ideal.

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