GATE 2014 EE (EE2) – Question 21

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

For the ideal transformer circuit shown, find Thevenin voltage and impedance at x,y.

Diagram for GATE 2014 EE (EE2) question 21

$2\sin\omega t$ V, 4 Ω
$\sin\omega t$ V, 1 Ω
$\sin\omega t$ V, 2 Ω
$2\sin\omega t$ V, 0.5 Ω

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Correct answer: (A) $2\sin\omega t$ V, 4 Ω

Explanation

With the secondary open,no primary current flows in an ideal transformer,so the1Ωresistor has no drop. The1:2turns ratio doubles open-circuit voltage to2sinωt. To find impedance,short the independent voltage source and reflect the primary1Ωthrough the square of the ratio:Zth=2²×1=4Ω. Hence **A**.