Question

A galvanometer of resistance $20\Omega$ is to be converted into an ammeter of range $1\mathrm{A}$. If a current of $1\mathrm{mA}$ produces full scale deflection, the shunt required for the purpose is}

• A. $0.01\Omega$
• B. $0.05\Omega$
• C. $0.02\Omega$
• D. $0.04\Omega$

Hint:

For ammeter conversion, $S = \frac{I_g G}{I - I_g}$.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Shunt resistance $S = \frac{I_g G}{I - I_g}$.
Step 2: Detailed Explanation:
$I_g = 1$ mA, $G = 20\Omega$, $I = 1$ A. $S = \frac{1 \times 10^{-3} \times 20}{1 - 1 \times 10^{-3}} = \frac{0.02}{0.999} \approx 0.02\Omega$.
Step 3: Final Answer:
The shunt required is $0.02\Omega$.