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JEE Main & Advanced Physics Wave Mechanics Question Bank Self Evaluation Test - Waves

  • question_answer
    A source producing sound of frequency 170 Hz is approaching a stationary observer with a velocity\[17m{{s}^{-1}}\]. The apparent change in the wavelength of sound heard by the observer is (speed of sound in air \[=340m{{s}^{-1}}\])

    A)  0.1 m

    B)  0.2 m

    C) 0.4 m

    D) 0.5 m

    Correct Answer: A

    Solution :

    [a] \[\lambda =\frac{v}{n}=\frac{340}{170}=2m\],  \[n'=\frac{340}{340-17}\times 170\] \[n'=178.9\,Hz\] Now \[\lambda '=\frac{v}{n'}=\frac{340}{178.9}=1.9\] \[\Rightarrow \,\lambda -\lambda '=2-1.9=0.1\]


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