Q. Two magnets of same size and mass make respectively 10 and $15\ oscillations\ per$ $minute$ at certain place. The ratio of their magnetic moments is

A) $4\ :9$
B) $9\ :4$
C) $2\ :3$
D) $3\ :2$
Explanation

(a) $T = 2\pi\sqrt{\frac{1}{MB_{H}}} \Rightarrow \frac{T_{1}}{T_{2}} = \sqrt{\frac{M_{2}}{M_{1}}} \Rightarrow \frac{M_{1}}{M_{2}} = \frac{T_{2}^{2}}{T_{1}^{2}} = \frac{(60/15)^{2}}{(60/10)^{2}} = \frac{4}{9}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.