A plane wave of sound traveling in air is incident upon a plane surface of a liquid. The angle of incidence is $60^o.$ The speed of sound in air is $300 \,m /s$ and in the liquid it is $600\, m /s .$ Assume Snell’s law to be valid for sound waves.

A string of length $1\,\,m$ and linear mass density $0.01\,\,kgm^{-1}$ is stretched to a tension of $100\,\,N.$ When both ends of the string are fixed, the three lowest frequencies for standing wave are $f_1, f_2$ and $f_3$. When only one end of the string is fixed, the three lowest frequencies for standing wave are $n_1, n_2$ and $n_3$. Then

If vibrations of a string are to be increased by a factor of two, then tension in the string must be made

The tension of a stretched string is increased by $69\%$. In order to keep its frequency of vibration constant, its length must be increased by .... $\%$

A person is producing wave in string by moving his hand first up and then down. If frequency is $\frac{1}{8}\,Hz$ then find out time taken by particle which is at a distance of $9\,m$ from source to move to lower extreme first time .... $s$ . (Given $\lambda  = 24\, m$)

When an air column at $15\,^oC$ and a tunning fork are sounded together then $4$ beats per second are produced, the frequency of the fork is less then that of air column. When the temperature falls to $10\,^oC$ , then the beat frequency decreases by one. The frequency of the fork will be ..... $Hz$ $[V_{sound}$ at $0\,^oC = 332\,m/s]$