A galvanmeter has a coil of resistance $200 \Omega$ with a full scale deflection at $20 \mu \mathrm{~A}$. The value of resistance to be added to use it as an ammeter of range $(0-20)$ mA is:

JEE Main · 2024 · 09 Apr 2024 · Shift 1 · Current Electricity

A galvanmeter has a coil of resistance

200Ω

with a full scale deflection at

20 μ A

. The value of resistance to be added to use it as an ammeter of range

(0 - 20)

mA is:

Answer: (B)

Shunt:

i = i_{g} (\frac{G}{S} + 1)

20 \times 1 0^{- 3} = 20 \times 1 0^{- 6} (\frac{200}{S} + 1) \Rightarrow \frac{200}{S} = 999 \Rightarrow S \approx 0.20 Ω

. Option (2).

JEE Main · 2024 · 09 Apr 2024 · Shift 1 · Single correct option