JEE Main & Advanced Sample Paper JEE Main - Mock Test - 24

  • question_answer
    In an a.c. circuit the voltage applied is\[\operatorname{E}={{E}_{0}}\sin \,\,\omega t\]. The resulting current in the circuit is \[I={{I}_{0}}\sin \left( \omega t-\frac{\pi }{2} \right)\]. The power consumption in the circuit is given by

    A) \[P=\sqrt{2}{{E}_{0}}{{I}_{0}}\]

    B)        \[P=\frac{{{E}_{0}}{{I}_{0}}}{\sqrt{2}}\]

    C) \[\operatorname{P}=zero\]         

    D)        \[\operatorname{P}=\frac{{{E}_{0}}{{I}_{0}}}{2}\]

    Correct Answer: C

    Solution :

    We know that power consumed in a.c. circuit is given by, \[\operatorname{P}=\,\,{{E}_{rms}}.\,{{I}_{rms}}\cos \,\phi \] Here, \[E=\,\,{{E}_{0}}\,sin\omega t\] \[I\,\,=\,\,{{I}_{0}}\sin \left( \omega t-\frac{\pi }{2} \right)\] which implies that the phase difference, \[\phi =\frac{\pi }{2}\] \[\therefore \,\,\,\,P={{E}_{rms}}.\,{{I}_{rms}}.\cos \frac{\pi }{2}=0\] \[\left( \because \,\,\cos \frac{\pi }{2}=0 \right)\]


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