Book excerpt: This book has been written for the students of B.Sc., Physics of various Indian Universities. The book covers the syllabi, prescribed by Madras, Bharathiyar, Bharathidhasan, Madurai Kamaraj and Manonmaniam Sundaranar Universities. SI System of Units has been used throughout the text. Proper care has been taken in dealing with the subject with modern outlook. A large number of questions and problems have been given at the end of each Chapter. Students should attempt to tackle them properly for better insight and understanding of the subject.