BCECE Engineering BCECE Engineering Solved Paper-2012

  • question_answer
    A resistor R, inductor L and a capacitor C are connected in series to an oscillator of frequency v. If the resonant frequency is \[{{v}_{r}},\] then the current lags behind the voltage, when

    A) \[v=0\]

    B)         \[v<{{v}_{r}}\]

    C)  \[v>{{v}_{r}}\] 

    D)         \[v={{v}_{r}}\]                                 

    Correct Answer: C

    Solution :

    The current will lag behind the voltage when reactance of inductor is more than the reactance of capacitor i.e., \[\omega L>\frac{1}{\omega c}\]                 or            \[\omega >\frac{1}{\sqrt{LC}}\]                 or            \[2\pi v>\frac{1}{\sqrt{LC}}\]                                 \[v>\frac{1}{2\pi \sqrt{LC}}\]                 or            \[v>{{v}_{r}}\] where \[{{v}_{r}}\]is the resonant frequency.


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