This book is meant for the students of B.E., B. Tech., B.Sc., and A.M.I.E. students. It provides the fundamental concepts of Modern Physics through various applications. It provides step-by-step solutions of topics. A set of solved numericals, theoretical questions and numerical problems at the end of each chapter provides the students to understand each topic clearly. Important topics that have been included are length contraction, variation of mass with velocity, Compton effect, proof of Heisenberg's uncertainty principle, complementarity principle and Doppler effect.