The present book is written for first-year graduate students in physics, chemistry, electrical engineering, and material sciences. Dynamics, quantum mechanics, thermodynamics, statistical mechanics, lectromagnetism, and solid-state physics at the undergraduate level are prerequisite. The authors believe that the students should learn physics, starting from the bottom up and following all theoretical developments with step-by-step calculations. We have included many problems, most of them elementary excercises in the text. The students learn key concepts more firmly by working out these problems.