Question

A $100\mu A$ ammeter has an internal resistance of $100\Omega$. For extending its range to measure $500\mu A$, the shunt resistance required is of

• A. 20.0 $\Omega$
• B. 22.22 $\Omega$
• C. 25.0 $\Omega$
• D. 50.0 $\Omega$

Answer 1

The correct option is C 25.0 $\Omega$

$R_{sh}=\frac{R_a}{m-1}=\frac{100}{\frac{500}{100}-1}=25.0\Omega$
$=25.0\Omega$