# A galvanometer is used in laboratory for detecting the null point in electrical experiments. If,

Question:

A galvanometer is used in laboratory for detecting the null point in electrical experiments. If, on passing a current of $6 \mathrm{~mA}$ it produces a deflection of $2^{\circ}$, its figure of merit is close to :

1. (1) $333^{\circ} \mathrm{A} /$ div.

2. (2) $6 \times 10^{-3} \mathrm{~A} / \mathrm{div}$.

3. (3) $666^{\circ} \mathrm{A} / \mathrm{div}$.

4. (4) $3 \times 10^{-3} \mathrm{~A} / \mathrm{div}$

Correct Option: 4

Solution:

(4) Given,

Current passing through galvanometer, $I=6 \mathrm{~mA}$

Deflection, $\theta=2^{\circ}$

Figure of merit of galvanometer

$=\frac{I}{\theta}=\frac{6 \times 10^{-3}}{2}=3 \times 10^{-3} \mathrm{~A} / \mathrm{div}$