GATE 2026 EE – Question 24

Electric Circuits · Network Theorems: Thevenin, Norton, Superposition and Maximum Power Transfer theorem · 1 mark · Multiple choice

For the circuit shown, which one of the following options correctly identifies the Thevenin’s equivalent parameters between nodes Y and Z?

Diagram for GATE 2026 EE question 24

$V_{TH}=100$ V, $R_{TH}=10\ \text{k}\Omega$
$V_{TH}=140$ V, $R_{TH}=0\ \Omega$
$V_{TH}=100$ V, $R_{TH}=0\ \Omega$
$V_{TH}=140$ V, $R_{TH}=10\ \text{k}\Omega$

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Correct answer: (B) $V_{TH}=140$ V, $R_{TH}=0\ \Omega$

Explanation

Take $W$ as the reference (0 V). The 100 V source fixes $V_X=100$ V, and the 20 V source between $X$ and $Y$ fixes $V_Y=V_X+20=120$ V. The other 20 V source fixes $V_Z=-20$ V. So the open-circuit voltage between $Y$ and $Z$ is $120-(-20)=140$ V. Both nodes are held by ideal voltage sources, so the resistance looking in is 0 Ω regardless of the resistors: $V_{TH}=140$ V, $R_{TH}=0$.