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. 0.08
• B. 0.09
• C. 0.1
• D. 0.91

Answer 1

Answer: (C)

0.1

Answer 2

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, $G=36\,\Omega ,\,S=4\Omega$
$\therefore$ $\frac{{{i}_{g}}}{i}=\frac{4}{36+4}=\frac{4}{40}$
$\Rightarrow$ ${{i}_{g}}=\frac{i}{10}$
$\therefore$ $1000\times \frac{{{i}_{g}}}{i}=\frac{1}{10}\times 100$
$\Rightarrow$ $\frac{{{i}_{g}}}{i}$