If a magnetic dipole of moment M situated in the direction of a magnetic field B is rotated by $180^

Question

If a magnetic dipole of moment M situated in the direction of a magnetic field B is rotated by $180^{\circ}$, then the amount of work done is\

Professor PC Thomas Classes · Answer

Work done in rotating the magnetic dipole of moment M in a magnetic field B from position $	heta_{1}$ to $	heta_{2}$ is\ $\mathrm{W}=\mathrm{MB}\left(\cos 	heta_{1}-\cos 	heta_{2}ight)$\ Here, $	heta_{1}=0^{\circ}, 	heta_{2}=180^{\circ}$\ $	herefore \mathrm{W}^{\prime}=\mathrm{MB}\left(\cos 	heta^{\circ}-\cos 180^{\circ}ight)=2 \mathrm{MB}$\