GATE 2016 EC (EC3) – Question 43
In the circuit shown, the current i in amperes, with its indicated downward direction, is ________.
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Show answer and explanation
Correct answer: -1.05 to -0.95
Explanation
Take the outer bottom/right wire as zero potential. The right 8 V source fixes the upper node at 8 V. If the centre node is V, the lower source makes the node below it V−8.
KCL for the centre/lower supernode gives $(V-8)+V+V+(V-8)=0$, so V=4 V. The upper node sends 4 A down the central 1 Ω resistor and 1 A through the current source; its right voltage source therefore carries 5 A upward.
At the right middle junction, 4 A enters from the centre and 5 A leaves upward. Thus the downward wire current is **−1 A**.