question_answer 7)

A bar magnet of magnetic moment lies aligned with the direction of a uniform magnetic field of 0.22 T.                 (a) What is the amount of work required by an external torque to turn the magnet so as to align its magnetic moment, (i) normal to the field direction, (ii) opposite to the field direction ?                 (b) What is the torque on the magnet in cases (i) and (ii)?  

Answer:

(a) (i) Using                                                 .                 (ii)Taking as we get                                                 (b) (i) Using we get                                                                 (ii) Since