Question

A millimeter of range of $10mA$ gives full-scale deflection for a current of $100mA$, when a shunt of $0.1\Omega$ is connected in parallel to it. The coil of the milliammeter has a resistance of

• A. $0.9\Omega$
• B. $1\Omega$
• C. $1.1\Omega$
• D. $0.11\Omega$

Answer 1

The correct option is A $0.9\Omega$

Voltage of the millimeter=$(100-10)mA\times 0.1\Omega$

$=90mA\times 0.1=0.009V$

$\therefore$ Resistance of the millimeter coil=$\frac{0.009V}{10mA}=0.9\Omega$