CET Karnataka Medical CET - Karnataka Medical Solved Paper-2007

  • question_answer
    An inductance of \[\left( \frac{200}{\pi } \right)\] mH, a capacitance pf \[\left( \frac{{{10}^{-3}}}{\pi } \right)\]F and a resistance of 10\[\Omega \] are connected in series with an AC source 220 V, 50 Hz. The phase angle of the circuit is

    A)  \[\frac{\pi }{6}\]

    B)  \[\frac{\pi }{4}\]

    C)  \[\frac{\pi }{2}\]

    D)  \[\frac{\pi }{3}\]

    Correct Answer: B

    Solution :

    The phase angle \[(\theta )\]between I and V is given by\[\tan \theta =\frac{{{X}_{L}}-{{X}_{C}}}{R}\]where,\[{{X}_{L}}=2\pi fL\] ?(i) \[=2\pi \times 50\times \left[ \frac{200}{\pi }\times {{10}^{-3}} \right]\] \[=20\Omega \] \[{{X}_{C}}=\frac{1}{2\pi fC}\] \[=\frac{1\times \pi }{2\pi \times 50\times {{10}^{-3}}}\]\[=10\Omega \] and \[R=10\Omega \] Substituting values of \[{{X}_{L}},{{X}_{C}}\]and R in Eq. (i), we get\[\tan \theta =\frac{20-10}{10}=1\] \[\Rightarrow \] \[\tan \theta =\tan \frac{\pi }{4}\] \[\therefore \] \[\theta =\frac{\pi }{4}\] The phase angle of the circuit is \[\frac{\pi }{4}.\]


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