Wave optics describes the connection between waves and rays of light. According to the wave theory of light, the light is a form of energy which travels through a medium in the form of transverse wave motion. The speed of light in a medium depends upon the nature of the medium. Wave optics also called Physic optics deals with the study of various phenomena such as polarization, diffraction, interference and other occurrences where ray approximation of geometric optics cannot be done. Thus, the section of optics that deals with the behaviour of light and its wave characteristics is said to be wave optics.
In wave optics, the approximation is carried out by using ray optics for the estimation of the field on a surface. Further, it involves integrating ray-estimated field over a mirror, lens or aperture for the calculation of the scattered or transmitted field. The derivation of laws of refraction and reflection using Huygens law is often asked in exams. The Brewster law and the angular width expression of the central maximum of the diffraction pattern are frequently asked. Besides the derivation and the theory, the numerical problems from various topics are asked in the exams.