J & K CET Medical J & K - CET Medical Solved Paper-2000

  • question_answer
    In an AC circuit the instantaneous values of emf and current are E = 200 sin 314t volt and\[i=\frac{1}{2}\sin \] ampere. The average power consumed in watts is:

    A)  200                                       

    B)  100

    C)  50                                         

    D)  25

    Correct Answer: D

    Solution :

                     The rate of dissipation of energy in an electrical circuit is called power. The power of an alternating current circuit depends upon the phase difference between the voltage and current, it is given by \[P={{E}_{rms}}\times {{I}_{rms}}\times \cos \phi \] where\[{{E}_{rms}}\]and\[{{I}_{rms}}\]are root mean square value of voltage and current. \[{{E}_{rms}}=\frac{{{E}_{0}}}{\sqrt{2}}=\frac{200}{\sqrt{2}}\]                 \[{{I}_{rms}}=\frac{{{I}_{0}}}{\sqrt{2}}=\frac{1}{2\sqrt{2}}\]                 \[\phi =\frac{\pi }{3}\] \[\therefore \]  \[P=\frac{200}{\sqrt{2}}\times \frac{1}{2\sqrt{2}}\times \cos \frac{\pi }{3}\] \[\Rightarrow \]               \[P=25W\]


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