Question

The ratio of the magnetic moments of two bar magnets is 4 : 5. If the deflection produced by the first one in magnetometer in tan B position is 45${}^o$, the deflection due to second magnet kept at the same distance is

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

Answer 1

Answer: (C)

${45}^o<\theta <{60}^o$

$\frac{M_1}{M_2}=\frac{\tan {\theta }_1}{\tan {\theta }_2}$

$\Rightarrow \frac{\tan {\theta }_1}{\tan {\theta }_2}=\frac{4}{5}\Rightarrow \tan {\theta }_2=\frac{5\tan {\theta }_1}{4}=\frac{5\tan {45}^o}{4}=1.25$

${\theta }_2={\tan }^{-1}\left(1.25\right)={51.34}^0$

${45}^o<{\theta }_2<{60}^o$