Q111 / 180 · NEET 2017 · Physics

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?

  • A
    10 Hz
  • Correct answer
    B
    20 Hz
  • C
    30 Hz
  • D
    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.

Hence, the correct answer is option: 'B'.

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