BCECE Engineering BCECE Engineering Solved Paper-2010

  • question_answer
    Two sound waves, each of amplitude A and frequency \[\omega ,\] superpose at a point with phase difference of \[\frac{\pi }{2}.\] The amplitude and frequency of the resultant wave are respectively

    A) \[\frac{A}{\sqrt{2}},\frac{\omega }{2}\]                                

    B) \[\frac{A}{\sqrt{2}},\omega \]

    C) \[\sqrt{2A,}\frac{\omega }{2}\]

    D)        \[\sqrt{2}A,\omega \]

    Correct Answer: D

    Solution :

    Let \[{{y}_{1}}=A\sin (\omega t)\] and \[{{y}_{2}}=A\sin \left( \omega t+\frac{\pi }{2} \right)\] Resultant amplitude \[{{R}^{2}}={{A}^{2}}+{{A}^{2}}+2{{A}^{2}}\cos \left( \frac{\pi }{2} \right)\] \[{{R}^{2}}=2{{A}^{2}}+2{{A}^{2}}\times 0\] \[{{R}^{2}}=2{{A}^{2}}\]                 \[\Rightarrow \]               \[R=\sqrt{2}A\] However, both will have the same frequency on superimposing.


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