Question

Two magnets when placed in $\tan A$ position at the same distance cause deflections of ${30}^o$ and ${60}^o$. The ratio of their magnetic moments is :

• A. $3:1$
• B. $1:3$
• C. $1:2$
• D. $2:1$

Answer 1

Answer: (B)

$1:3$

In $\tan A$ position , the deflection of the needle is given by
$\frac{{\mu }_o}{4\pi }\frac{2M}{d^3}=B_H\tan {\theta }_A$
$\frac{\tan {\theta }_A}{\tan {\theta }_B}=\frac{M_A}{M_B}$
$\frac{M_A}{M_B}=\frac{1}{3}$