AMU Medical AMU Solved Paper-2014

  • question_answer
    Two open organ pipes on sounding together produce 5 beats per second. If the length of the smaller pipe is 0.66m, the length of the larger pipe would be

    A)  0.95m                  

    B)  0.85 m

    C)  0.75 m                 

    D)  0.67 m

    Correct Answer: D

    Solution :

                     The given,                 \[{{n}_{2}}-{{n}_{1}}=5\,Hz\]                                      .... (i) (If the speed of sound in air is 330 m/s) \[\frac{v}{2{{l}_{2}}}-\frac{v}{2{{l}_{1}}}=5\]        [For open organ pipe, \[n=\frac{v}{2l}\]]                                 \[\frac{v}{2}\left[ \frac{1}{0.66}-\frac{1}{{{l}_{1}}} \right]=5\]                                 \[\frac{330}{2}\left[ \frac{100}{66}-\frac{1}{{{l}_{1}}} \right]=5\]                                 \[33\left[ \frac{50}{33}-\frac{1}{{{l}_{1}}} \right]=1\]                                 \[=\frac{50}{33}-\frac{1}{{{l}_{1}}}=\frac{1}{33}\]                                                 \[\frac{1}{{{l}_{1}}}=\frac{50}{33}-\frac{1}{33}\Rightarrow \frac{1}{{{l}_{1}}}=\frac{49}{33}\]                                                 \[{{l}_{1}}=0.67\,m\]


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