MGIMS WARDHA MGIMS WARDHA Solved Paper-2008

  • question_answer
    The maximum particle velocity in a wave motion is half the wave velocity. Then the amplitude of the wave is equal to

    A) \[\frac{\lambda }{4\pi }\]                                            

    B) \[\frac{2\lambda }{\pi }\]

    C) \[\frac{\lambda }{2\pi }\]                                            

    D) \[\lambda \]

    Correct Answer: A

    Solution :

    For a wave, \[y=a\sin \frac{2\pi }{\lambda }=(vt-x)\]                ...(i) Differentiating Eq (i) w.r.t. t, we get \[\frac{dy}{dt}=\frac{2\pi \,va}{\lambda }\cos \frac{2\pi }{\lambda }(vt-x)\] Now, maximum velocity is obtained when \[\cos \frac{2\pi }{\lambda }(vt-x)=1\] \[\therefore \]  \[{{v}_{\max }}={{\left( \frac{dy}{dt} \right)}_{\max }}\]                 \[=\frac{2\pi va}{\lambda }\] But         \[{{v}_{\max }}=\frac{v}{2}\]                        (given) \[\therefore \]  \[\frac{v}{2}=\frac{2\pi va}{\lambda }\] \[\Rightarrow \]               \[a=\frac{\lambda }{4\pi }\]


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