InterviewSolution
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InterviewSolution
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A box P and a coil Q are connected in series with an ac source of variable frequency. The emf of the source is constant at 10 V. Box P xontains a capacitance of `32 Omega`. Coil Q has a self inductance of 4.9 mH and a resistance of `68 Omega` in series. The frequency is adjusted so that maximum current flows in P and Q. The impedance of P at this frequency isA. `77 Omega`B. `36 Omega`C. `40 Omega`D. `125 Omega` |
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Answer» Correct Answer - A As this circuit is a series LCR circuit, cuttent will be maximum at reasonance , i.e. `omega = (1)/(sqrt(LC))v =(1)/(sqrt((4.9 xx10^(-3))(10^(-6)))=(10^5)/(7) rad s^(-1)` with `I=(V)/(R ) =(10)/((32+68))=(1)/(10)A` so the impedance, `Z_(P)=[R_(1)^(2)+(1//omegaC)^(2)]^(1//2) = sqrt(5924)=77 Omega`. |
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