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GATE 2016 EE (EE2) – Question 22

Electric Circuits · Transient response of DC and AC networks, sinusoidal steady-state analysis, resonance, two port networks, balanced three phase circuits, star-delta transformation, complex power and power factor in AC circuits · 1 mark · Numerical answer

Load voltage and current are $v(t)=100\sin\omega t$ V and $i(t)=10\sin(\omega t-60^\circ)+2\sin3\omega t+5\sin5\omega t$ A. Average load power in watts is ________.

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Correct answer: 249.0 to 251.0

Explanation

Only equal-frequency voltage and current components contribute nonzero average power. The voltage has only the fundamental, so the current harmonics average to zero in the product vi.

Fundamental rms values are 100/√2 V and 10/√2 A, with 60° displacement. Thus $P=(100/\sqrt2)(10/\sqrt2)\cos60^\circ=$ **250 W**.

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