Question

The resistance of a galvanometer is $999\Omega$. It is shunted by $1\Omega$ resistance. If the current in the circuit is ${10}^{-2}\text{A},$ then the current through galvanometer is

• A. ${10}^{-6}\text{A}$
• B. ${10}^{-5}\text{A}$
• C. ${10}^{-4}\text{A}$
• D. ${10}^{-3}\text{A}$

Answer 1

The correct option is B ${10}^{-5}\text{A}$

For a galvanometer, shunt resistance is
$S=\frac{G}{\frac{I}{I_g}-1}\Rightarrow \frac{I}{I_g}-1=\frac{G}{S}$
$I_g=\frac{I}{\frac{G}{S}+1}=\frac{{10}^{-2}}{\frac{999}{1}+1}={10}^{-5}A$