JEE Main 2026 — Jan 21, Shift 1 — Physics solution

JEE Main2026Jan 21, Shift 1Physics

The heat generated in 1 minute between points A and B in the given circuit, when a battery of 9V with internal resistance of 1 $Ω$ is connected across these points is ____________ J.

Your answer

Solution

The bridge satisfies $\frac{1}{2} = \frac{2}{4}$ , so it is balanced — no current flows through the middle 1 $Ω$ resistor.

The network between A and B reduces to two parallel branches: $(1 + 2) = 3Ω$ in parallel with $(2 + 4) = 6Ω$ , giving $R_{A B} = \frac{3 \cdot 6}{3 + 6} = 2Ω$ .

Total circuit resistance with the 1 $Ω$ internal resistance: $3Ω$ . Current $i = 9/3 = 3$ A.

Heat dissipated between A and B in 60 s: $H = i^{2} R_{A B} t = 9 \times 2 \times 60 = 1080$ J.

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