This textbook has been designed to meet the needs of B.Sc. Second Semester students of Physics as per Common Minimum Syllabus prescribed for Patna University and other Universities and Colleges under the recommended National Education Policy 2020 in Bihar. The theory paper is comprised of Four Units and starts with Free Forced and Damped Harmonic Oscillations, Lissajous Figures and Stationary Waves, Wave Front and Wave Motion, Sound Waves, Sharpness of Resonance, Sonometer, Beats, Musical Instruments, Newton's Formula for Velocity of Sound and Laplace's Correction, Musical Scale & Consonance etc. These all are lucidly explained in this book.