JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा Question Bank ac Circuits

  • question_answer
    The coefficient of induction of a choke coil is 0.1H and resistance is \[12\,\Omega \]. If it is connected to an alternating current source of frequency 60 Hz, then power factor will be [RPET 1997]

    A)            0.32                                          

    B)            0.30

    C)            0.28                                          

    D)            0.24

    Correct Answer: B

    Solution :

                       \[\cos \varphi =\frac{R}{Z}=\frac{R}{\sqrt{{{R}^{2}}+{{\omega }^{2}}{{L}^{2}}}}\]                   \[=\frac{12}{\sqrt{{{(12)}^{2}}+4\times {{\pi }^{2}}\times {{(60)}^{2}}\times {{(0.1)}^{2}}}}\]\[\Rightarrow \,\,\cos \varphi =0.30\]


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