RAJASTHAN ­ PET Rajasthan PET Solved Paper-2004

  • question_answer
    Two waves are represent by \[{{y}_{1}}=\alpha \sin \left( \omega t+\frac{\pi }{6} \right),{{y}_{2}}=a\cos \,\omega t,\]the resultant amplitude will be

    A)  \[a\]                

    B)  \[a\sqrt{2}\]

    C)  \[a\sqrt{3}\]               

    D)  \[2a\]

    Correct Answer: C

    Solution :

     \[{{y}_{1}}=a\sin \left( \omega t+\frac{\pi }{6} \right)\] and      \[{{y}_{2}}=a\cos \omega t=a\sin (\omega t+\lambda /2)\] \[\therefore \] \[R=\sqrt{a_{1}^{2}+a_{2}^{2}+2{{a}_{1}}{{a}_{2}}\cos ({{\phi }_{2}}-{{\phi }_{1}})}\] \[=\sqrt{{{a}^{2}}+{{a}^{2}}+2{{a}^{2}}\times \cos \left( \frac{\pi }{2}-\frac{\pi }{6} \right)}\] \[=\sqrt{2{{a}^{2}}+2{{a}^{2}}\times \frac{1}{2}}\] \[R=\sqrt{3a}\]


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