The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260 Hz. What is…

The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260 Hz. What is the fundamental frequency of the system?
  1. 10 Hz
  2. 20 Hz
  3. 30 Hz
  4. 40 Hz

Solution

Two successive frequencies of closed pipe
nv4l=220 ....(i)
n+2v4l=260 ......(ii)
Dividing (ii) by (i), we get
n+2n=260220=1311
11n+22=13n
n=11
So, 11v4l=220
v4l=20
So fundamental frequency is 20 Hz.

Asked in: NEET 2017

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