Q 12-03-073JEE MainJEE Main 2025 (28 Jan, Shift 2)Easy
The value of current $I$ in the electrical circuit given below, when the potential at A is equal to the potential at B, will be ______ A.
Numerical value type. Enter your answer.
Answer: 2
With $V_A = V_B$ no current flows through the $30\ \Omega$ resistor, and the bridge is balanced:
$$\frac{10}{20} = \frac{R}{40} \Rightarrow R = 20\ \Omega$$
The $30\ \Omega$ can be removed: $(10 + 20) = 30\ \Omega$ in parallel with $(20 + 40) = 60\ \Omega$ gives $20\ \Omega$.
$$I = \frac{40}{20} = 2\ \text{A}$$
Solution by Sreeraj P, M.Sc Physics