This book basically caters to the needs of undergraduates and graduates physics students in the area of modern physics, specially particle and nuclear physics. Lecturers/tutors may use it as a resource book. The contents of the book are based on the syllabi currently used in the undergraduate courses in USA, U.K., and other countries. The book is divided into 10 chapters, each chapter beginning with a brief but adequate summary and necessary formulas, tables and line diagrams followed by a variety of typical problems useful for assignments and exams. Detailed solutions are provided at the end of each chapter.