Waves Ques 28
28. Velocity of sound waves in air is $330$ $ m / s$. For a particular sound wave in air, a path difference of $40 $ $cm$ is equivalent to phase difference of $1.6 $ $\pi$. The frequency of this wave is
[1990]
(a) $165 $ $Hz$
(b) $150 $ $Hz$
(c) $660 $ $Hz$
(d) $330 $ $Hz$
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Answer:
Correct Answer: 28.(c)
Solution:
- (c) From $\Delta x=\frac{\lambda}{2 \pi} \Delta \phi$,
$\lambda=2 \pi \frac{\Delta x}{\Delta \phi}=\frac{2 \pi(0.4)}{1.6 \pi}=0.5 $ $m$
$f=\frac{v}{\lambda}=\frac{330}{0.5}=660 $ $Hz$
BETA
