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

  • question_answer
    An LCR series circuit is under resonance. If \[{{l}_{m}}\] is current amplitude, \[{{V}_{m}}\] is voltage amplitude, R is the resistance, Z is the impedance, \[{{X}_{L}}\] is the inductive reactance and \[{{X}_{C}}\] is the capacitive reactance, then:

    A) \[{{l}_{m}}=\frac{Z}{{{V}_{m}}}\]                

    B) \[{{l}_{m}}=\frac{{{V}_{m}}}{{{X}_{L}}}\]

    C) \[{{l}_{m}}=\frac{{{V}_{m}}}{{{X}_{C}}}\]             

    D) \[{{l}_{m}}=\frac{{{V}_{m}}}{R}\]

    Correct Answer: D

    Solution :

    (d) \[{{l}_{m}}=\frac{{{V}_{m}}}{R}\] Impedance of the circuit, \[Z=\sqrt{{{R}^{2}}+{{\left( {{X}_{L}}-{{X}_{C}} \right)}^{2}}}\] Resonance, \[{{X}_{L}}={{X}_{C}}\]             \[Z=R\] \[\therefore {{l}_{m}}=\frac{{{V}_{m}}}{Z}=\frac{{{V}_{m}}}{R}\]


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