NEET Sample Paper NEET Sample Test Paper-16

  • question_answer In a certain organ pipe three successive resonance frequencies are observed at 425,595 and 765 Hz respectively. If the speed of sound in air is 340 m/s, the length of the pipe is:

    A) 2 m                             

    B) 1 m                 

    C)      1.5 m               

    D)     2.5 m

    Correct Answer: B

    Solution :

    Successive frequency are in the ratio 425:595:765 i.e., 5:7:9. This indicates that only odd harmonics are present. Hence it is a closed organ pipe. In a closed Organ pipe the frequency of the 5th harmonic is 5v/4 fi where v is the velocity of sound. So,\[\frac{5v}{4\ell }=425\]where \[v=340\,m/s.\] \[\therefore \]\[\ell =1\,m.\] Hence, the correction option is (b).


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