Question

A moving coil galvanometer has a resistance of $9.8\Omega$ and gives a full scale deflection when a current of $10mA$ passes through it. The value of the shunt required to convert it into a milliammeter to measure current upto $500mA$ is

• A. $0.4\Omega$
• B. $2.0\Omega$
• C. $0.2\Omega$
• D. $0.02\Omega$

Answer 1

Answer: (C)

$0.2\Omega$

Shunt $S=\frac{G}{n-1}$
where $n=\frac{I}{I_g}=\frac{500mA}{10mA}=50$
$\therefore S=\frac{9.8}{50-1}ohm=\frac{9.8}{49}ohm=0.2ohm$.