Question

A short magnet produces a deflection of ${30}^o$ when placed at some distance in $\tan A$ position of the magnetometer. If another magnet of same length and double the pole strength is kept at the same distance in $\tan B$ position, the deflection produced is

• A. ${30}^o$
• B. ${60}^o$
• C. ${45}^o$
• D. $0^o$

Answer 1

The correct option is A ${30}^o$

Given,
$\frac{{\mu }_0}{4\pi }\frac{2Md}{d^3}=B_H\tan {\theta }_A$
$\frac{{\mu }_0}{4\pi }\frac{2\times Md}{d^3}=B_H\tan {\theta }_B$
From the above two equations, $\tan {\theta }_A=\tan {\theta }_B$
$\Rightarrow {\theta }_B={30}^{\circ }$ since given ${\theta }_A={30}^{\circ }$