For waves propagating in a medium, identify the property that is independent of the others

Two tuning forks $A$ and $B$ produce $8\,beats/s$ when sounded together. $A$ gas column $37.5\,cm$ long in a pipe closed at one end resonate to its fundamental mode with fork $A$ whereas a column of length $38.5\,cm$ of the same gas in a similar pipe is required for resonance with fork $B$. The frequencies of these two tuning forks, are

In a Fraunhofer's diffraction obtained by a single slit aperture, the value of path difference for $n^{th}$ order of minima is

The wave described by $y = 0.25\,\sin \,\left( {10\pi x - 2\pi t} \right)$ , where $x$ and $y$ are in $meters$ and $t$ in $seconds$ , is a wave travelling along is

The figure represents the instantaneous picture of a transverse harmonic wave traveling along the negative $x$-axis. Choose the correct alternative $(s)$ related to the movement of the nine points shown in the figure.  The stationary points is/are

Four tuning forks of frequencies $200,201, 204$ and $206\, Hz$ are sounded together.  The beat frequency will be