This textbook is a comprehensive up-to-date volume providing the concepts and applications of contemporary physics for the use of students pursuing undergraduate engineering degree courses in institutions affiliated to Indian Universities Located in different zones. A modern description of interaction between atoms (and molecules) is given along with discussions of topics such as lasers, nanotechnology, magnetic properties of materials, superconductivity and applications. Many riders at the end of each chapter are the salient features of this textbook. This may in turn serve the purpose of GATE aspirants and others aspiring for faculty positions in Universities, Colleges and research institutions through written examinations.