Question

A milliammeter of range 10 mA and resistance $9\Omega$ is joined in a circuit as shown. The metre gives full-scale deflection for current l when A and B are used as its terminals, i.e., current enters at A and leaves at B (C is left isolated). The value of I is

• A. 100 mA
• B. 900 mA
• C. 1 A
• D. 1.1 A

Answer 1

The correct option is B 900 mA

$I$ gives full scale deflection.
Therefore,
$I\frac{0.1}{0.1+9}=0.01\Rightarrow I=0.91A\approx 900mA$