(a)[3]
Light of a single wavelength is incident on a diffraction grating. Explain the roles of diffraction and interference in producing the first order maximum formed by the diffraction grating.
(b)[3]
The diffraction grating shown in Fig. 5.1 is used with light of wavelength $486\,\text{nm}$. The orders of the maxima formed are displayed on the screen in Fig. 5.1. The angle between the two second order maxima is $59.4^\circ$. Calculate the number of lines per millimetre of the grating.