Use Fig. 5.1 to find the frequency of wave X.
A second wave Z, which has the same frequency as wave X, also passes point P. Wave Z has intensity 2I. The phase difference between the two waves is 90^\circ. On Fig. 5.1, sketch how the displacement y of wave Z varies with time t. Show your working.
A double-slit interference arrangement is used to find the wavelength of light from a laser, as shown in Fig. 5.2. The slit separation is 0.45\,\text{mm}. The fringes are observed on a screen at a distance D from the double slit. The fringe width x is recorded for a range of distances D. The way x varies with D is shown in Fig. 5.3.
Use the gradient of the line in Fig. 5.3 to find the wavelength, in nm, of the laser light.
The slit separation is increased. State and explain what effect, if any, this has on the graph in Fig. 5.3.
The slit separation is increased. State and explain the effect, if any, on the graph in Fig. 5.3.