The following phenomenon cannot be observed for sound waves:

The minimum distance of the reflector surface from the source to hear the echo of sound is ..... $m$.

The speed of sound waves in a fluid depends upon:

$A$ plane sound wave passes from medium $1$ into medium $2$. The speed of sound in medium $1$ is $200 \, m/s$ and in medium $2$ is $100 \, m/s$. The ratio of the amplitude of the transmitted wave to that of the incident wave is:

At what temperature will the speed of sound be nearly $1.5$ times its value at $N.T.P.$ (in $^{\circ} C$)?

The densities of two diatomic gases at constant temperature and pressure are $d_1$ and $d_2$. The ratio of the speed of sound in these gases is: