Question

A short bar magnet with its $N-$ pole pointing north produces a null point at a distance $15cm$ from its midpoint. If this magnet is used in $\tan A$ position of deflection magnetometer at a distance $15cm$ from the magnetic needle, the deflection is

• A. ${\tan }^{-1}\left(3/2\right)$
• B. ${\tan }^{-1}\left(3/4\right)$
• C. ${\tan }^{-1}\left(2\right)$
• D. ${\tan }^{-1}\left(1/2\right)$

Answer 1

The correct option is C ${\tan }^{-1}\left(2\right)$

For null deflection in $\tan A$ position,
$\frac{\tan {\theta }_1}{\tan {\theta }_2}=2$
Here, the deflection obtain at same distance for the same magnet used.
$\therefore \tan \theta =2$
or $\theta ={\tan }^{-1}2$