Question

Assertion :The force required for the rotation of a copper disc becomes greater when it is made to rotate with its rim between the poles of a magnet, the disc at the same time becoming heated by the eddy current induced in the metal Reason: Law of conservation of energy is followed by eddy current

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Eddy current losses is related to the

$p_e=k_e{f}^2{B}^{2}m$,

$k_e$ = constant ,

f = frequency Hz ,

$B_m$ = magnetic field density.

When magnet present, therefore, present of magnetic field creates eddy current losses in form of heat. Then the force required to rotate is more because more work has to do. Some energy dissipated into heat.