Question

Assertion : A disc-shaped magnet is leviated above a superconducting material that has been cooled by liquid nitrogen.

Reason: Superconductors repel a magnet.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

Correct option  (a) Both A and R are true and R is the correct explanation of A

Explanation:

Since superconductors exist only below, a certain critical temperature and above that temperature they behave like normal materials. When magnet is placed above superconductor and cooled using liquid nitrogen. The induced magnetic field inside the superconductor is exactly equal and opposite in direction to the applied magnetic field, so that they cancel within the super conductor. These poles will repel each other and the force of repulsion is enough to float the magnet.