JEE Main 2024 Physics question
A galvanometer has a coil of resistance 200 Ω with a full scale deflection at 20 μA. The value of resistance to be added to use it as an ammeter of range (0 – 20) mA is:
Answer: (B)
Solution
i = /S + 1): 20 × 10⁻³ = 20 × 10⁻⁶(200/S + 1), so 200/S = 999 and S ≈ 0.2 Ω (connected in parallel).