Waves Ques 34
34. A tuning fork is used to produce resonance in a glass tube. The length of the air column in this tube can be adjusted by a variable piston. At room temperature of $27^{\circ} C$ two successive resonances are produced at $20 $ $cm$ and $73 $ $cm$ of column length. If the frequency of the tuning fork is $320$ $ Hz$, the velocity of sound in air at $27^{\circ} C$ is
[2018]
(a) $330 $ $m / s$
(b) $339 $ $m / s$
(c) $300 $ $m / s$
(d) $350 $ $m / s$
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Answer:
Correct Answer: 34.(b)
Solution:
- (b) Two successive resonance are produced at $20 $ $cm$ and $73$ $ cm$ of column length
$\therefore \quad \frac{\lambda}{2}=(73-20) \times 10^{-2} m $
$\Rightarrow \quad \lambda=2 \times(73-20) \times 10^{-2} $
$\text{ Velocity of sound, } v=n \lambda $
$= \quad 2 \times 320[73-20] \times 10^{-2} $
$ = \quad 339.2 $ $ms^{-1}$
BETA
