Q. A short bar magnet placed with its axis at $30{^\circ}$ with a uniform external magnetic field of $0.16$ tesla experiences a torque of magnitude 0.032 J. The magnetic moment of bar magnet will be
A) 0.23 J/T
B) 0.40 J/T
C) 0.80 J/T
D) Zero
Explanation
(b) Torque, $\tau = {MB}_{H}\sin\theta\ $
$\Rightarrow \ \ 0.032 = M \times 0.16\sin{30{^\circ}}$
$\Rightarrow \ \ \ \ \ \ \ \ \ M = 0.4\ J/T$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.