Q. Two short magnets having magnetic moments in the ratio $27\ :8$, when placed on opposite sides of a deflection magnetometer, produce no deflection. If the distance of the weaker magnet is $0.12\ m$ from the centre of deflection magnetometer, the distance of the stronger magnet from the centre is
A) 0.06 $m$
B) $0.08\ m$
C) 0.12 $m$
D) 0.18 $m$
Explanation
(d) $\frac{M_{1}}{M_{2}} = \left( \frac{d_{1}}{d_{2}} \right)^{3} \Rightarrow \frac{27}{8} = \left( \frac{d_{1}}{0.12} \right)^{3}$
$\Rightarrow \frac{3}{2} = \frac{d_{1}}{0.12} \Rightarrow 0.18\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.