A current of \( 2\times10^{-5}\,\mathrm{A} \) produces 25 division deflection in a galvanometer. The resistance of the galvanometer coil is 4 Ω. The figure of merit of galvanometer is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 8\times10^{-7} \) ampere/division
The figure of merit of a galvanometer is the current needed to produce a deflection of one division, so it is the current divided by the deflection. The resistance of the coil is not needed.
\( \displaystyle \text{figure of merit} = \frac{I}{\theta} = \frac{2\times10^{-5}\,\mathrm{A}}{25\ \text{divisions}} = 8\times10^{-7}\ \text{ampere/division} \)