Question

Work done in turning a magnet of magnetic moment M by an angle of 90? from the mgnetic meridian is n times the corresponding work done to turn through an angle of 60?, where n is

• A. 01-Feb
• B. 2
• C. 01-Apr
• D. 1

Answer 1

Answer: (B)

2

Answer 2

W1 = - MB (cos 90? - cos 0?) = MB
W2 = - MB (cos 60? - cos 0?)
= -MB$\left(\frac{1}{2}-1\right)=\frac{1}{2}$ MB
Which is $=\frac{1}{2}$ W1
As, W1 = n W2 $\quad\quad$ ? n = 2