STANDARD Physics Power in AC Circuits MCQ Question
An inductor of reactance 1 Ω and a resistor of 2 Ω are connected in series to the terminals of a 6 V (rms) ac source. The power dissipated in the circuit is
8 W
12 W
14.4 W
18 W
Correct Answer
Detailed Explanation
Here, Xₗ = 1 Ω, R = 2 Ω, Vₘₛ = 6 V. Impedance of the circuit Z = √(Xₗ² + R²) = √(1² + 2²) = √5 Ω. Iₘₛ = Vₘₛ/Z = 6/√5 A. Power dissipated P = Vₘₛ Iₘₛ cos φ = Vₘₛ Iₘₛ R/Z = 6 × 6/√5 × 2/√5 = 72/5 = 14.4 W.
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