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12th Class Physics Alternating Current / प्रत्यावर्ती धारा Question Bank MCQ - Alternating Currents

  • question_answer
    A series LCR circuit with \[R=22\,\Omega ,L=1.5\,H\]and \[C=40\mu F\] is connected to a variable frequency 220 V AC 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?

    A) 2000 W                        

    B) 2200 W

    C) 2400 W                        

    D) 2500 W

    Correct Answer: B

    Solution :

    (b) 2200 W When the frequency of the supply equals to the natural frequency of circuit, resonance occurs. \[\therefore Z=R=22\,\Omega \] and \[{{l}_{rms}}=\frac{{{V}_{rms}}}{Z}=\frac{220}{22}=10\,A\] Average power transferred per cycle, \[P={{V}_{rms}}{{l}_{rms}}\cos \,0{}^\circ =220\times 10\times 1=2200\,W\]


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