(a)[2]
State the meaning of diffraction of a wave.
(b)[2]
Plane wavefronts are incident on a slit, as shown in Fig. 5.1. Finish Fig. 5.1 by drawing four wavefronts that emerge from the slit.
(c)[3]
As shown in Fig. 5.2, monochromatic light is incident normally on a diffraction grating with $650$ lines per millimetre. An image (the zero order) is seen for light with an angle of diffraction of zero. For incident light of wavelength $590\,\text{nm}$, determine how many orders of diffracted light can be seen on each side of the zero order.
(d)[1]
The images in Fig. 5.2 are observed, beginning with the zero order and then moving to higher order numbers. State how the appearance of the images changes as the order number rises.