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A series LCR circuit has resistance 200 Ω and is connected to an AC source of 220 V, 50 Hz. If the capacitor is removed, the current lags the supply voltage by 30°. If the inductor is removed, the current leads the supply voltage by 30°. The power consumed by the complete LCR circuit is
- 305 W
- 210 W
- Zero W
- 242 W
Correct answer: 242 W
Solution
Removing C gives tan30 = XL/R; removing L gives tan30 = XC/R, so XL = XC. The full circuit is at resonance, Z = R, and P = V^2/R = 220^2/200 = 242 W.
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