AMU Medical AMU Solved Paper-2005

  • question_answer
    An alternating current is given by \[\text{I}=\text{ }{{\text{I}}_{\text{1}}}\text{ cos }\omega \text{t}+{{I}_{2}}\text{ sin }\omega t,\]the root mean square current is given by

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

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

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

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

    Correct Answer: C

    Solution :

                     The equation of alternating current (AC) is given by                                 \[I={{I}_{1}}\cos \omega \,t+{{I}_{2}}\sin \omega \,t\] The resultant current                 \[{{I}_{0}}=\sqrt{{{I}_{1}}^{2}+{{I}_{2}}^{2}}\] Also, rms value of current is given by                 \[{{I}_{rms}}=\frac{{{I}_{0}}}{\sqrt{2}}\] \[\Rightarrow \]               \[{{I}_{rms}}=\sqrt{\frac{{{I}_{1}}^{2}+{{I}_{2}}^{2}}{2}}\]


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