Q. Two magnets held together in earth’s magnetic field with same polarity together make 12 $vib - \min^{- 1}{and}$ when opposite poles together make 4 $vib - {\min^{- 1}.}{The}$ ratio of magnetic moments is
A) 9 :1
B) 1 : 3
C) 1 : 9
D) 10 : 8
Explanation
(d) $\frac{M_{1}}{M_{2}} = \frac{T_{2}^{2}{+ T}_{1}^{2}}{T_{2}^{2}{- T}_{1}^{2}} = \frac{n_{2}^{2} + n_{1}^{2}}{n_{1}^{2} - n_{2}^{2}}$
$= \frac{4^{2} + 12^{2}}{12^{2} - 4^{2}} = \frac{160}{128} = 10\ :8$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.