Question

Work done in turning a magnet of magnetic moment M by an angle of 90° from the magnetic meridian is n times the corresponding work done to turn through an angle of 60°, where n is(a) 1/2(b) 2(c) 1/4(d) 1

Answer 1

Answer:

B) 2

Explanation:

Magnetic moment = M

Initial angle through which magnet is turned (q1) = 90°

Final angle through which magnet is turned (q2) = 60°.

Work done in turning the magnet, through 90° (W1) = MB (cos 0°-cos 90°)  = MB

Work done in turning the magnet, through 60°(W2) = MB (cos 0°-cos 60°)  = 0.5MB

= W1 = 2W2

= W1 = nw2 ( Given)

Thus n = 2

Therefore the corresponding work done to turn through an angle of 60° is 2