Question

A voltmeter of $250mV$ range having a resistance of $10\Omega$ is converted into an ammeter of $250mA$ range. The value of necessary shunt is (nearly)

• A. $2\Omega$
• B. $0.1\Omega$
• C. $1\Omega$
• D. $10\Omega$

Answer 1

Answer: (C)

A voltmeter of $250mV$ range having resistance of $10\Omega$
$\therefore V_g=G{I}_g$
$\Rightarrow 250\times 10^{-3}=10\times I_g$
$\Rightarrow I_g=25\times 10^{-3}A$
Shunt required to convert this voltmeter into ammeter.
$S=\frac{G{I}_g}{I-I_g}$
$=\frac{10\times \left(25\times 10^{-3}\right)}{250\times 10^{-3}-25\times 10^{-3}}=\frac{10}{9}=1\Omega$