Question

On producing the waves of frequency $1000 \, Hz$ in a Kundt's tube, the total distance between $6$ successive nodes is $85 \, cm$ . Speed of sound in the gas-filled in the tube is

• A. $300\,ms^{- 1}$
• B. $350\,ms^{- 1}$
• C. $340\,ms^{- 1}$
• D. $330\,ms^{- 1}$

Answer 1

Answer: (C)

Frequency of wave, $\nu=1000\,Hz$
Number of successive nodes $= 6$
The total distance between six successive nodes = $85\,cm$
From the relation between the distance of nodes and wavelength of the wave
$\text{s} = 8 5 = \frac{\left(\text{n} - 1\right) \lambda }{2} = \frac{\left(6 - 1\right) \lambda }{2} = \frac{5 \lambda }{2}$
where, $\lambda $ = wavelength of the wave
$\therefore \lambda = \frac{2 \times 8 5}{5} = 3 4 \text{cm} = 0 \text{.} 3 4 \text{m}$
Hence, the speed of sound in the gas = v $\lambda $
$=1000\times 0.34=340\,ms^{- 1}$