Q. A bar magnet $A$ of magnetic moment $M_{A}$ is found to oscillate at a frequency twice that of magnet $B$ of magnetic moment $M_{B}$ when placed in a vibrating $magneto - meter$. We may say that
A) $M_{A} = 2M_{B}$
B) $M_{A} = 8M_{B}$
C) $M_{A} = 4M_{B}$
D) $M_{B} = 8M_{A}$
Explanation
(c) $c = \frac{1}{2\pi}\sqrt{\frac{MB_{H}}{I}} \Rightarrow v \propto \sqrt{M}$
$\Rightarrow \frac{v_{A}}{v_{B}} = \sqrt{\frac{M_{A}}{M_{B}}} \Rightarrow \frac{2}{1} = \sqrt{\frac{M_{A}}{M_{B}}} \Rightarrow M_{A} = 4\ M_{B}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.