Q. The torque on a bar magnet due to the earth’ magnetic field is maximum when the axis of the magnet is
A) Perpendicular to the field of the earth
B) Parallel of the vertical component of the earth’s field
C) At an angle of $33{^\circ}$ with respect $N$-$S$ direction
D) Along the North-South ($N$-$S$) direction
Explanation
(a) Torque on a bar magnet in earths magnetic field $(B_{H})$ is $\tau = MB_{H}\sin\theta.\ \tau$ will be maximum if $\sin\theta =$ maximum $i.e.\ \theta = 90{^\circ}$. Hence axis of the magnet is perpendicular to the field of earth
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.