A bar magnet of magnetic moment 2 · 5 JT^-1 lies aligned with the direction of a uniform magnetic field of 0 · 32 T. (a) Find the amount of work done…

(ii) \[\begin{aligned} \mathrm{W} & =-\mathrm{mB}\left(\operatorname{Cos} 180^{\circ}-\operatorname{Cos} 0^{\circ}\right) \\ & =2 \mathrm{mB} \\ & =2 \times 0.8 \\ \mathrm{~W} & =1.6 \mathrm{~J} \end{aligned} \]

(b) (i) \[\begin{aligned} \tau & =\mathrm{mB} \sin \theta \\ & =0.8 \mathrm{Nm} \end{aligned} \]

(ii) \[\tau=0 \]