JEE Main & Advanced Physics Wave Mechanics Question Bank Critical Thinking

  • question_answer
    The ends of a stretched wire of length L are fixed at \[x=0\] and \[x=L.\] In one experiment, the displacement of the wire is \[{{y}_{1}}=A\sin (\pi x/L)\sin \omega t\] and energy is \[{{E}_{1}}\], and in another experiment its displacement is \[{{y}_{2}}=A\sin (2\pi x/L)\sin 2\omega t\] and energy is \[{{E}_{2}}\]. Then  [IIT-JEE (Screening) 2001]

    A)            \[{{E}_{2}}={{E}_{1}}\]     

    B)            \[{{E}_{2}}=2{{E}_{1}}\]

    C)            \[{{E}_{2}}=4{{E}_{1}}\]   

    D)            \[{{E}_{2}}=16{{E}_{1}}\]

    Correct Answer: C

    Solution :

                Energy (E) µ (Amplitude)2 (Frequency)2                    Amplitude is same in both the cases, but frequency 2\[\omega \] in the second case is two times the frequency \[(\omega )\] in the first case. Hence \[{{E}_{2}}=4{{E}_{1}}\].


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