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

  • question_answer
    A pipe of length \[{{\ell }_{1}}\], closed at one end is kept in a chamber of gas of density\[{{\rho }_{1}}\]. A second pipe open at both ends is placed in a second chamber of gas of density \[{{\rho }_{2}}\]. The compressibility of both the gases is equal Calculate the length of the second pipe if frequency of first overtone in both the cases is equal

    A)  \[\frac{4}{3}{{\ell }_{1}}\sqrt{\frac{{{\rho }_{2}}}{{{\rho }_{1}}}}\]

    B)  \[\frac{4}{3}{{\ell }_{1}}\sqrt{\frac{{{\rho }_{1}}}{{{\rho }_{2}}}}\]

    C) \[{{\ell }_{1}}\sqrt{\frac{{{\rho }_{2}}}{{{\rho }_{1}}}}\]

    D) \[{{\ell }_{1}}\sqrt{\frac{{{\rho }_{1}}}{{{\rho }_{2}}}}\]

    Correct Answer: B

    Solution :

    [b] Frequency of first overtone in closed pipe, \[v=\frac{3v}{4{{\ell }_{1}}}\sqrt{\frac{P}{{{\rho }_{1}}}}\]                 ?. (i) Frequency of first overtone in open pipe, \[v'=\frac{1}{{{\ell }_{2}}}\sqrt{\frac{P}{{{\rho }_{2}}}}\]                  ?. (ii) From equation (i) and (ii) \[\Rightarrow \,\,{{\ell }_{2}}=\frac{4}{3}{{\ell }_{1}}\sqrt{\frac{{{\rho }_{1}}}{{{\rho }_{2}}}}\]


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