J & K CET Medical J & K - CET Medical Solved Paper-2013

  • question_answer
    If the alternating current\[I={{I}_{1}}\cos \omega t+{{I}_{2}}\] \[\sin \omega t\] then   the  rms current is given by

    A)  \[\frac{{{I}_{1}}+{{I}_{2}}}{\sqrt{2}}\]

    B)  \[\frac{|{{I}_{1}}+{{I}_{2}}|}{\sqrt{2}}\]

    C)  \[\sqrt{\left( \frac{I_{1}^{2}+I_{2}^{2}}{\sqrt{2}} \right)}\]

    D)  \[\sqrt{\frac{I_{1}^{2}+I_{2}^{2}}{\sqrt{2}}}\]

    Correct Answer: C

    Solution :

     The equation of AC is \[I={{I}_{1}}\cos \omega t+{{I}_{2}}\sin \omega L\] The resultant current is given by \[{{i}_{0}}=\sqrt{I_{1}^{2}+I_{2}^{2}}\] Hence, the rms current from relation is \[{{I}_{rms}}=\frac{{{I}_{0}}}{\sqrt{2}}=\frac{\sqrt{I_{1}^{2}+I_{2}^{2}}}{\sqrt{2}}\] \[=\sqrt{\frac{I_{1}^{2}+I_{2}^{2}}{2}}\]


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