The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe…

The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe which is  L meter long. The length of the open pipe will be
  1. L
  2. 2L
  3. L2
  4. 4L

Solution

Let the length of open organ pipe be $L'$.

Frequency of second overtone of open organ pipe is given as, f1=3v2L', where v is speed of sound in air.

Frequency of first overtone of closed pipe is given as, f2=3v4L.

According to question, f1=f2

3v2L'=3v4LL'=2L.

Hence, length of open organ pipe must be twice the length of closed organ pipe.

Asked in: NEET 2016 (Phase 2)

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