Physics - Current Electricity Question with Solution | TestHub

Let $G$ be resistance of galvanometer and $I^{\prime }$ be the current passing through the galvanometer produces full scale deflection. If $I$ is the maximum current, and since, $G$ and $S$ are in parallel so, the potential difference between them will be same. Then,

$$\begin{gathered} I^{{}^{\prime }}G=I_2\text{S} \\ \Rightarrow 72I^{{}^{\prime }}=8I_2 \\ \Rightarrow I_2=9I^{{}^{\prime }} \\ \Rightarrow I=I^{{}^{\prime }}+I_2=10I^{{}^{\prime }} \end{gathered}$$

So the percentage of total current passes through galvanometer is

$\frac{I^{{}^{\prime }}}{I}\times 100$ $=\frac{I^{{}^{\prime }}}{10I^{{}^{\prime }}}\times 100=10\%$