Question

A $36\Omega$ galvanometer is shunted by resistance of $4\Omega .$ The percentage of the total current, which passes through the galvanometer is

• A. 8%
• B. 9%
• C. 10%
• D. 91%

Answer 1

Answer: (C)

Let G be resistance of galvanometer and $i_g$ the current which on passing through the galvanometer produces full scale deflection. If $i$ is the maximum current, and since, G and S are in parallel.
$i_g\times G=(i-i_g)\times S$
$\Rightarrow$ $\frac{i_g}{i}=\frac{S}{S+G}$
Given, $G=36\Omega ,S=4\Omega$
$\therefore$ $\frac{i_g}{i}=\frac{4}{36+4}=\frac{4}{40}$
$\Rightarrow$ $i_g=\frac{i}{10}$
$\therefore$ $1000\times \frac{i_g}{i}=\frac{1}{10}\times 100$
$\Rightarrow$ $\frac{i_g}{i}$