Wheatstone Bridge & Metre Bridge question from MHT CET 2025 (21 Apr, Shift 2)

Answer: (c)

1. Reading unchanged with S open or closed means no current flows through S, so $V_B = V_D$.
2. At B (no current into S): $I_P = I_Q$.
3. At D (no current from S): current coming in through R goes out through G, so $I_R = I_G$.
4. So the answer is (c) $I_R = I_G$.