JCECE Engineering JCECE Engineering Solved Paper-2015

  • question_answer
    In the circuit shown in the figure, the \[AC\] source gives a voltage\[V=10\sin (1000t)\]. Neglecting source resistance, the voltmeter and ammeter reading will be

    A) \[20\sqrt{\frac{125}{538}}V\]and\[\frac{10}{\sqrt{538}}A\]

    B) \[10\sqrt{\frac{250}{538}}V\]and\[\frac{10}{\sqrt{538}}A\]

    C) \[\sqrt{\frac{250}{538}}V\]and\[\frac{1}{\sqrt{538}}A\]

    D)  \[\sqrt{\frac{125}{539}}V\]and\[\frac{1}{\sqrt{538}}A\]

    Correct Answer: B

    Solution :

    Impedance of the circuit is                 \[Z=\sqrt{{{R}^{2}}+{{({{X}_{L}}-{{X}_{C}})}^{2}}}\]                 \[R=8\Omega \]                                               (given)                 \[{{X}_{L}}=\omega L=1000\times 10\times {{10}^{-3}}=10\Omega \]                 \[{{X}_{C}}=\frac{1}{\omega C}=\frac{1}{2000\times 20\times {{10}^{-6}}}=25\Omega \] \[\Rightarrow \]               \[Z=\sqrt{64+{{(15)}^{2}}}=\sqrt{64+225}=\sqrt{269}\]                 \[{{I}_{\max }}=\frac{{{V}_{0}}}{Z}=\frac{10}{\sqrt{269}}A\]                 \[{{I}_{rms}}=\frac{{{I}_{\max }}}{\sqrt{2}}=\frac{10}{\sqrt{538}}A\]                 \[{{V}_{rms}}={{I}_{rms}}\times \sqrt{{{5}^{2}}+{{(15)}^{2}}}\]                 \[=\frac{10}{\sqrt{538}}\times \sqrt{25+225}=10\sqrt{\frac{250}{538}}V\]


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