In series LR circuit, $ R=18 \Omega $ and impedance is $ 33 \Omega $. An r.m.s. voltage $ 220 \mathrm{~V} $ is applied across the circuit. The true power consumed in a.c. circuit is:

Question

In series LR circuit, $ R=18 \Omega $ and impedance is $ 33 \Omega $. An r.m.s. voltage $ 220 \mathrm{~V} $ is applied across the circuit. The true power consumed in a.c. circuit is:, $ 220 \mathrm{~W} $, $ 400 \mathrm{~W} $, $ 600 \mathrm{~W} $, $ 800 \mathrm{~W} $

MARKS App · Accepted Answer

Reactance of an inductor is given by, X L = ω L , where L represents inductance. Net impedance of LR circuit is given by, Z L = X L 2 + R 2 = 33 Ω (given) Power factor of this circuit is given by, cos ϕ = R Z L ⇒ cos ϕ = 18 33 Now, average power in AC circuit is given by, P = e rms 2 Z L cos ϕ ⇒ P = 220 2 33 × 18 33 = 800 W

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