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Assertion: A thin aluminium disc, spinni...

Assertion: A thin aluminium disc, spinning freely about a centre pivot, is quickly brought to rest when . placed between the poles of a strong U-shaped magnet
Reason:A current induced in a disc rotating in a magnetic field produces a force which tends to oppose the disc's motion.

A

If both the assertion and reason are true statement and reason is correct explanation of the assertion .

B

If both the assertion and reason are true statement but reason is not a correct explanation of the assertion .

C

If the assertion is true but the reason is a false statement.

D

If both assertion and reason are false statements.

Text Solution

Verified by Experts

The correct Answer is:
A
This effect is due to the production of 'eddy currents' in the aluminium disc. They are produced due to the motion of disc in magnetic field. According to Lenz's law they oppose this motion ( which is the cause of their production ) and eventually bring the disc to a stop .
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