Self Assessment Quiz

1. What is the two-fluid model of superconductors ?

2. Although the dc conductivity of a superconductor can be infinite, why is it finite in an ac electric field ?

3. State the two London equations. Based on them, how can Meissner effect be explained ?

4. For use in superconducting magnets, are superconductors with low or high critical fields desirable ?

5. A substance has a transition temperature of 100 K and the zero-temperature critical field is 100 Tesla. What field has to be applied at 50 K in order to destroy superconductivity in this material ?

6. Why is there a limit to the the quantity of current that can pass through a superconductor beyond which it becomes normal (non-superconducting)?