In an AC circuit, the instantaneous voltage is V = 100 sin(ωt) V and the instantaneous current is I = 100 sin(ωt + π/3) mA. What is the average power dissipated in the circuit over a complete cycle?
Answer and explanation
Correct answer: C. 2.5 W
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- Step 1: The average power dissipated in an AC circuit is given by: , where is the phase difference between voltage and current.
- Step 2: Extract peak values from the given equations:
- Step 3: The phase difference is , so the power factor is .
- Step 4: Compute average power:
Answer
2.5 W
Why not the others: '5.0 W' forgets the power factor ; '10.0 W' multiplies peak values directly () without the factors or power factor; 'Zero' incorrectly assumes a phase angle (wattless condition).
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