Question -
Answer -
(a)Magnetic moment, M =1.5 J T−1
Magneticfield strength, B = 0.22 T
(i)Initial angle betweenthe axis and the magnetic field, θ1 = 0°
Final angle between theaxis and the magnetic field, θ2 = 90°
The work required tomake the magnetic moment normal to the direction of magnetic field is given as:

(ii) Initial anglebetween the axis and the magnetic field, θ1 = 0°
Final angle between theaxis and the magnetic field, θ2 = 180°
The work required tomake the magnetic moment opposite to the direction of magnetic field is givenas:

(b)For case (i): 
∴Torque, 

For case (ii): 
Torque, 
