Q. When two magnetic moments are compared using equal distance method the deflections produced are $45{^\circ}$ and $30{^\circ}$. If the length of magnets are in the ratio $1\ :2$, the ratio of their pole strength is
A) $3\ :1$
B) $3\ :2$
C) $\sqrt{3}\ :1$
D) $2\sqrt{3}\ :1$
Explanation
(d) $\frac{M_{1}}{M_{2}} = \frac{\tan\theta_{1}}{\tan\theta_{2}} \Rightarrow \frac{m_{1}L_{1}}{m_{2}L_{2}} = \frac{\tan\theta_{1}}{\tan\theta_{2}}$
$\Rightarrow \frac{m_{1}}{m_{2}} = \frac{2}{1} \times \frac{\tan{45{^\circ}}}{\tan{30{^\circ}}} = \frac{2\sqrt{3}}{1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.