Two waves of sound having intensities $I$ and $4I$ interfere to produce interference pattern. The phase difference between the waves is $\pi /2$ at point $A$ and $\pi$ at point $B$. Then the difference between the resultant intensities at $A$ and $B$ is

A massless rod is suspended by two identical strings $AB$ and $CD$ of equal length. A block of mass $m$ is suspended from point $ O $ such that $BO$ is equal to $’x’$. Further, it is observed that the frequency of $1^{st}$ harmonic (fundamental frequency) in $AB$ is equal to $2^{nd}$ harmonic frequency in $CD$. Then, length of $BO$ is

$y = a\,cos\,(kx -\omega t)$ superposes on another wave giving a stationary wave having node at $x = 0$ . What is the equation of the other wave 

A man fires a bullet standing between two cliffs. First echo is heard after $3\, seconds$ and second echo is heard after $5\, seconds$. If the velocity of sound is $330\,m/s$, then the distance between the cliffs is .... $m$

If $n_1 , n_2$ and $n_3$ are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency $n$ of the string is given by

A transverse wave is described by the equation $y = {y_0}\,\sin \,2\pi \,\left[ {ft - \frac{x}{\lambda }} \right]$ . The maximum particle velocity is equal to four times the wave velocity if