Velocity of sound waves in air is $330 \mathrm{~m} / \mathrm{s}$. For a particular sound wave in air, path…
Velocity of sound waves in air is $330 \mathrm{~m} / \mathrm{s}$. For a particular sound wave in air, path difference of 40 cm is equivalent to phase difference of $1.6 \pi$ : frequency of this wave is
165 Hz
150 Hz
660 Hz
330 Hz
Solution
Given: $\phi=1.6 \pi$ and $\lambda=\frac{\mathrm{V}}{\mathrm{f}}=\frac{330}{\mathrm{f}}$...(i)
We know,
Phase difference $\phi=\frac{2 \pi \times x}{\lambda}$
where x is path difference.
$\therefore \quad 1.6 \pi=\frac{2 \pi \times\left(40 \times 10^{-2}\right) \times \mathrm{f}}{330}$
...[From(i)]
$\mathrm{f}=660 \mathrm{~Hz}$