Two closed pipes produce 10 beats per second when emitting their fundamental nodes. If their lengths are in…

Two closed pipes produce 10 beats per second when emitting their fundamental nodes. If their lengths are in ratio of 25 : 26. Then, their fundamental frequency (in Hz) are
  1. 270, 280
  2. 260, 270
  3. 260, 250
  4. 260, 280

Solution

Here, $n_1 - n_2 = 10$ ...(i) Using $n_1 = \frac{v}{4l_1}$ and $n_2 = \frac{v}{4l_2}$ $\implies \frac{n_1}{n_2} = \frac{l_2}{l_1} = \frac{26}{25}$ ...(ii) On solving Eqs. (i) and (ii), we get $n_1 = 260\text{ Hz}, n_2 = 250\text{ Hz}$

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