Uttarakhand PMT Uttarakhand PMT Solved Paper-2007

  • question_answer
    A wave travelling along positive y-axis is given by\[y=A\text{ }sin\]\[(\omega -kx).\] If it is reflected from rigid boundary such that 80% amplitude is reflected, then equation of reflected wave is

    A) \[y=A\sin (\omega t+kx)\]

    B)  \[y=-0.8A\sin (\omega t+kx)\]

    C) \[y=0.8A\sin (\omega t+kx)\]

    D) \[y=A\sin (\omega t+0.8\,kx)\]

    Correct Answer: B

    Solution :

     On getting reflected from a rigid boundary the wave suffers an additional phase change of\[\pi \]. Thus, equation of reflected wave is given by \[y=0.8\text{ }A\text{ }sin(\omega t+kx+\pi )\] \[\therefore \] \[y=-0.8\text{ }A\text{ }sin(\omega t+kx)\]


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