Q. A short bar magnet of magnetic moment 0.4 J T⁻¹ is placed in a uniform magnetic field of 0.16 T. The magnet is in stable equilibrium when the potential energy is
A) – 0.082 J
B) 0.064 J
C) – 0.064 J
D) Zero
Explanation
[Solution from source] U = −MB cos θ; stable equilibrium is θ = 0, so U = −MB = −0.4 × 0.16 = −0.064 J. +0.064 J is the unstable (antiparallel) equilibrium. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.