Direction for: In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
Assertion: There are very small sporadic changes in the speed of rotation of the earth. Reason: Shifting of large air masses in the earths atmosphere produce a change in the moment of inertia of the earth causing its speed of rotation to change.A) If both assertion and reason are true and reason is the correct explanation of assertion
B) If both assertion and reason are true but reason is not the correct explanation of assertion
C) If assertion is true but reason is false
D) If both assertion and reason are false
Correct Answer: A
Solution :
As superconductors occur only below a particular temperature and above that temperature they behave as normal material so, if magnet is placed above superconductor and cooled by using nitrogen, then the magnetic field inside the superconductor is exactly equal and opposite in direction to applied magnetic field. Hence, they are cancelled within the superconductor so, these poles repel each other. Therefore, due to this force of repulsion, magnet is repelled.
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