Question

A galvanometer gives full deflection when a current of 0.3 mA is passed through it. The resistance of galvanometer is $100\Omega$. Now to convert it into an ammeter, a shunt of $1m\Omega$ is connected. The new range of this ammeter is:

• A. 3mA
• B. 30mA
• C. 3A
• D. 30A

Answer 1

The correct option is D 30A


$(n-1)i_g.S=i_g.G$
$S=\frac{G}{n-1}$
$n-1=\frac{100}{{10}^{-3}}={10}^5$
$n={10}^5$
new range = n {old range}
$={10}^5\times 0.3\times {10}^{-3}=30A$