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A series LCR circuit with R = 20 Omega , L = 1.5 H and C = 35 muFis connected to a variable-frequency 200 V a.c. supply. When the frequency of the supply equals the natural frequency of the circuit, what is the average power transferred to the circuit in one complete cycle ? |
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Answer» Solution :When FREQUENCY of the supply = natural frequency of circuit `v_(0) = 1/(2pi sqrt(LC)), X_(L) = X_( C)` and resonance takes place so that current `I_(rms) = V_(rms)/R = 200/20 = 10 A` As in resonance condition voltage and current are in same phase condition, (i.e. `PHI = 0^(@)`) hence average power `P_(av) = V_(rms).I_(rms). COS phi = 200 xx 10 cos 0^(@) = 2000 W` or 2kW. |
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