Question

In the experiment to determine the galvanometer resistance by half-deflection method, the plot of  \(\frac{1}{\theta}\) vs the resistance (R) of the resistance box is shown in the figure. The figure of merit of the galvanometer is .............. ×10^–1 A/division. [The source has emf 2V]

Answer 1

Correct answer is :  5

\(\mathrm{i}=\mathrm{K} \theta\)

\(\frac{2}{\mathrm{G}+\mathrm{R}}=\mathrm{K} \theta\)

\(\Rightarrow \frac{1}{\theta}=\frac{(\mathrm{G}+\mathrm{R}) \mathrm{K}}{2}=\mathrm{R}\left(\frac{\mathrm{K}}{2}\right)+\frac{\mathrm{KG}}{2}\)

Slope \( =\frac{\mathrm{K}}{2}=\frac{1}{4} \Rightarrow \mathrm{K}=0.5=5 \times 10^{-1} \mathrm{~A}\)