Q. A magnetic dipole is placed at right angles to the direction of lines of force of magnetic induction $B$. If it is rotated through an angle of 180${^\circ}$, then the work done is
A) $MB$
B) 2$\ MB$
C) $- 2\ MB$
D) Zero
Explanation
(d) $\theta_{1} = 90{^\circ},\ \theta_{2} = 270{^\circ},$
$W = - MB\lbrack cos270{^\circ} - cos90{^\circ}\rbrack =$zero
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.