Wheatstone Bridge & Metre Bridge question from MHT CET 2025 (22 Apr, Shift 1)

Answer: (b)

1. Zero current in G means the $6$ V cell is balanced by the p.d. across $R$: $V_R = 6$ V.
2. Then the $10$ V cell drives current only through $4\ \Omega$ and $R$: $I = \dfrac{10}{4+R}$
3. $\dfrac{10R}{4+R} = 6 \Rightarrow 10R = 24 + 6R \Rightarrow R = 6\ \Omega$
4. So the answer is (b) $6\ \Omega$.