Question

In an ammeter, $10\%$ of main current is passing through the galvanometer. If the resistance of the galvanometer is $G$, then the shunt resistance is

• A. $9G$
• B. $\frac{G}{9}$
• C. $90G$
• D. $\frac{G}{90}$

Answer 1

The correct option is B

$\frac{G}{9}$

We have,
${\text{I}}_{\text{g}}=10\%\text{of I}=0.1\text{I}$

We know, the shunt resistance is given by:
$\text{S}=\frac{{\text{GI}}_{\text{g}}}{\text{I}-{\text{I}}_{\text{g}}}=\frac{0.1\text{IG}}{\text{I}-0.1\text{I}}=\frac{\text{G}}{9}$