JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा JEE PYQ-Alternating Current

  • question_answer
    A sinusoidal voltage of peak value 283 V and angular frequency 320/s is applied to a series LCR circuit. Given that \[R=5\Omega ,\,L=25\,mH\] and \[C=1000\,\mu F\]. The total impedance, and phase difference between the voltage across the source and the current will respectively be-                     [JEE Online 09-04-2017]

    A) \[10\,\Omega \] and \[{{\tan }^{-1}}\,\left( \frac{5}{3} \right)\]

    B) \[7\,\Omega \] and \[{{45}^{\text{o}}}\]

    C) \[7\,\Omega \] and \[{{\tan }^{-1}}\left( \frac{5}{3} \right)\]

    D) \[10\,\Omega \,\] and \[{{\tan }^{-1}}\,\left( \frac{8}{3} \right)\]

    Correct Answer: B

    Solution :

    [b] \[{{e}_{0}}=283\,\,volt\,\]     \[\omega =320\]
    \[{{X}_{L}}\,=320\,\times 25\,\times {{10}^{-3}}\,=8\,\Omega \]
    \[{{X}_{C}}\,=\frac{1}{\omega C}=\,\frac{1}{320\,\times 1000\,\times {{10}^{-6}}}\]
    \[=\frac{1000}{320}\,=3.1\,\Omega \]
    \[R=5\,\Omega \]
    \[Z=\sqrt{{{R}^{2}}+{{({{X}_{L}}-{{X}_{C}})}^{2}}}\,=\sqrt{50}\,=7\,\Omega \]
    \[\tan \phi \,=\frac{{{X}_{L}}-{{X}_{C}}}{R}\]
    \[=1\,\,\,\,\,\,\,\,\,\,\phi ={{45}^{\text{o}}}\]


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