Q143 / 180 · NEET 2026 (Cancelled) · Physics
A galvanometer of resistance $100\ \Omega$ gives full scale deflection for a current of $1$ mA. It is converted into an ammeter of range $0 - 10$ A. The shunt required is :
- Correct answerA$0.01\ \Omega$
- B$0.10\ \Omega$
- C$1.0\ \Omega$
- D$0.001\ \Omega$
Solution
Given $G = 100\ \Omega$, $I_g = 1\text{ mA} = 10^{-3}\text{ A}$, and $I = 10\text{ A}$.
The shunt resistance $S$ required to convert a galvanometer into an ammeter is given by:
$S = \dfrac{I_g G}{I - I_g}$
Substituting the values:
$S = \dfrac{10^{-3} \times 100}{10 - 10^{-3}}$
Since $10 \gg 10^{-3}$, we can approximate $10 - 10^{-3} \approx 10$.
$S \approx \dfrac{0.1}{10} = 0.01\ \Omega$
Answer: $0.01\ \Omega$
The shunt resistance $S$ required to convert a galvanometer into an ammeter is given by:
$S = \dfrac{I_g G}{I - I_g}$
Substituting the values:
$S = \dfrac{10^{-3} \times 100}{10 - 10^{-3}}$
Since $10 \gg 10^{-3}$, we can approximate $10 - 10^{-3} \approx 10$.
$S \approx \dfrac{0.1}{10} = 0.01\ \Omega$
Answer: $0.01\ \Omega$
Hence, the correct answer is option: 'A'.