A current of \( 10^{-7}\,\mathrm{A} \) produces 50 division deflection in a galvanometer. The figure of merit would be:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( 2 \times 10^{-9}\,\mathrm{A/div} \)
The figure of merit of a galvanometer is the current needed to produce a deflection of one division:
\( \displaystyle G = \frac{I}{\theta} \)
\( \displaystyle G = \frac{10^{-7}\,\mathrm{A}}{50\,\mathrm{div}} = 0.02\times10^{-7}\,\mathrm{A/div} = 2\times10^{-9}\,\mathrm{A/div} \)
It is the reciprocal of the current sensitivity \( \theta/I \).