Question

A(0-50 A) moving coil ammeter has a voltage drop of 0.1 V across its terminals at full scale deflection. Then external shunt resistance (in milliohms) needed to extend its range to (0-500 A)is

• A. 0.22

Answer 1

The correct option is A 0.22
$I_{fs}=50A;V_m=0.1V$

$R_m=\frac{0.1}{50}$


$=2\times {10}^{-3}\Omega$

$\because m=10;$

$R_{sh}=\frac{R_m}{(m-1)}=\frac{2\times {10}^{-3}}{9}$

$=0.22m\Omega$