A and B are two wires whose fundamental frequencies are 256 Hz and 382 Hz respectively. When third harmonic of A and the second harmonic of B are sounded together, the number of beats heard in two second will be

In case of stationary wave pattern, which of the following statement is CORRECT ?

Out of the following musical instruments which is ' NOT ' a percussion instrument?

The enclosed air inside a closed box of rigid walls has pressure $P_1$. The density of air inside this box is constant. On heating the gas, the pressure of the enclosed air is increased from $P_1$ to $P_2$. Now it is observed that the sound travels $1.4$ times faster than at pressure $P_1$. The ratio $P_2$ by $P_1$ is