State, with reference to the direction in which energy propagates, what is meant by a transverse wave.
State the principle of superposition in waves.
As shown in Fig. 4.1, circular water waves can be generated by vibrating dippers at points P and Q. The waves from P alone have the same amplitude at point R as the waves from Q alone. The distance $PR$ is $44\,\text{cm}$ and the distance $QR$ is $29\,\text{cm}$. The dippers vibrate in phase with a period of $1.5\,\text{s}$ and produce waves with speed $4.0\,\text{cm s}^{-1}$.
Determine the wavelength of these waves.
Using the distances $PR$ and $QR$, explain why the water particles are at rest at point R.
A wave is formed on the surface of a different liquid. At one instant, Fig. 4.2 shows how the vertical displacement $y$ varies with distance $x$ along the liquid surface.
Determine the ratio $\frac{I_2}{I_1}$ for the wave at $x = 2.0\,\text{cm}$ and $x = 10.0\,\text{cm}$, where the intensities are $I_1$ and $I_2$ respectively.
State the phase difference, together with its unit, between the oscillations of the liquid particles at $x = 3.0\,\text{cm}$ and $x = 4.0\,\text{cm}$.