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

  • question_answer
    The power factor of an AC circuit having resistance R and inductance L (connected in series) and an angular velocity co is [AIEEE 2002]

    A) \[\frac{R}{\omega L}\]

    B) \[\frac{R}{{{({{R}^{2}}+{{\omega }^{2}}{{L}^{2}})}^{1/2}}}\]

    C) \[\frac{\omega L}{R}\]

    D) \[\frac{R}{{{({{R}^{2}}-{{\omega }^{2}}{{L}^{2}})}^{1/2}}}\]

    Correct Answer: B

    Solution :

    [b] From the relation, \[\tan \phi =\frac{\omega L}{R}\]
    Power factor, \[\cos \phi =\frac{1}{\sqrt{\,1+{{\tan }^{2}}\phi }}\]
                            \[=\frac{1}{\sqrt{\,1+{{\left( \frac{\omega L}{R} \right)}^{2}}}}\]
                \[=\frac{R}{\sqrt{\,{{R}^{2}}+{{\omega }^{2}}{{L}^{2}}}}\]


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