Waves - Result Question 32
32. 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
(a) $165 Hz$
(b) $150 Hz$
(c) $660 Hz$
(d) $330 Hz$
[1990]
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Answer:
Correct Answer: 32. (c)
Solution:
- (c) From $\Delta x=\frac{\lambda}{2 \pi} \Delta \phi$,
$\lambda=2 \pi \frac{\Delta x}{\Delta \phi}=\frac{2 \pi(0.4)}{1.6 \pi}=0.5 m$
$f=\frac{v}{\lambda}=\frac{330}{0.5}=660 Hz$
