Question

A galvanometer is used in the laboratory for detecting the null point in electrical experiments. If on passing a current of $6mA$ it produces a deflection of $2°$, its figure of merit is close to

• A. $6\times {10}^{-3}A/div.$
• B. $3\times {10}^{-3}A/div.$
• C. $666°A/div.$
• D. $333°A/div.$

Answer 1

The correct option is B

$3\times {10}^{-3}A/div.$

Step 1. Given data:

Current passing through the Galvanometer, $I=6mA$

$\Rightarrow I=6\times {10}^{-3}A$

Deflection in the Galvanometer, $\theta =2°$

Step 2. Calculating Figure of merit:

Figure of merit $=\frac{I}{\theta }$

$=\frac{6\times {10}^{-3}}{2}$

$\therefore$Figure of merit $=3\times {10}^{-3}A/div.$

Hence, correct option is (B).