This book is written specifically to address the course curriculum in Engineering Physics-I of the B. Tech syllabus of the Anna University. The book is designed to serve the needs of the first-year undergraduate students of all branches of engineering. It provides a sound understanding of the important phenomena in physics. The book exposes the students to fundamental knowledge in: 1 Ultrasonics and their applications in industry and medicine. 2 Properties and applications of lasers in industry and medicine. 3 Types of optical fibres, their geometries, and use in communication systems; types of optical sources, detectors, and sensors including endoscopes. 4 Characteristics of black body radiation and quantum concepts of radiation. 5 Science of crystallography for understanding the structure of solids including the nature of crystal defects. Key Features 1 Numerous worked-out examples in text to give students a sound understanding of the subject. 2 Chapter-end summary for quick revision of the important results. 3 Chapter-end short and long answer questions to stimulate discussion on the major themes in the chapter. 4 Chapter-end numerical problems with answers to help students assess their progress and familiarize them with many of the types of questions set in exams.