BHU PMT BHU PMT (Screening) Solved Paper-2006

  • question_answer
    Two closed organ pipes A and B, have the same length. A is wider than B. They resonate in the fundamental mode at frequencies n^ and rig respectively, then:

    A) \[{{n}_{A}}={{n}_{B}}\]

    B)  \[{{n}_{A}}>{{n}_{B}}\]

    C)  \[{{n}_{A}}<{{n}_{B}}\]                

    D)  either  or  depending on the ratio of their diameters

    Correct Answer: C

    Solution :

                     In closed organ pipe. First resonance occurs at \[\lambda /4\]. So, in fundamental mode of vibration of organ pipe\[\frac{\lambda }{4}=(l+0.3d)\]where 0.3d is necessary end correction. Frequency of vibration,                 \[n=\frac{v}{\lambda }=\frac{v}{4(l+0.3d)}\] As\[l\]is same, wider pipe A will resonate at a lower frequency, i.e.,\[{{n}_{A}}<{{n}_{B}}\]. Note: The value of end correction e is 0.6 r for closed organ pipe and 1.2r for an open organ pipe. where\[r\]is the radius of the pipe.


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