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 point$(s)$ is/are:

The equation of a wave is given by $Y = 7 \sin(7\pi t - 0.04\pi x + \frac{\pi}{3})$. What is the wave speed in $m/s$?

Select the correct statement about the reflection and refraction of a wave at the interface between medium $1$ and medium $2$.

If the equation of a transverse wave is $y = 5\sin 2\pi \left[ \frac{t}{0.04} - \frac{x}{40} \right]$,where distance is in $cm$ and time is in seconds,then the wavelength of the wave is .... $cm$.

The relation between phase difference $(\Delta \phi)$ and path difference $(\Delta x)$ is:

For the wave $y(x, t) = 3.0 \sin (36 t + 0.018 x + \pi / 4)$,plot the displacement $(y)$ versus time $(t)$ graphs for $x = 0, 2$ and $4 \; cm$. What are the shapes of these graphs? In which aspects does the oscillatory motion in a travelling wave differ from one point to another: amplitude,frequency,or phase?