This textbook has been specifically developed on the directives of National Education Policy (NEP 2020) and is as per latest curriculum of B.Sc. Physics (First Semester) for the University of Lucknow. The book comprised of Four units. Unit I cover Electromagnetic Nature of Light, Spacial and Temporal Coherence, Fresnel Biprism, Lloyd's Mirror, Thin Films, Michelson Interferometer, Febry Perot Interferometer and Etalon. Unit II includes Fresnel and Fraunhofer Diffractions, and Diffraction Grating, Principal Maxima and Missing Orders. Unit III highlights Rayleigh's criterion of resolution, Resolving power of grating and telescope. Unit IV describes the Optical Activity, Specific Rotation, Polarimeters, Jones Matrix, Metrics for polarizers and Retarding Plates are lucidly explained at the end of the book.