The phenomena we normally observe in nature can broadly be classified into two categories: those concerned with matter and those concerned with waves. Physics courses usually begin with discussion of phenomena dealing with mechanics of matter and properties of matter. Next comes the phenomena of waves. Of our five senses, two deal with the waves - hearing and seeing. Our contact with the external world is mainly through these two senses. Sound and light, though of entirely different nature, have many properties in common. In this IGNOU course, you will learn about waves in general. This unified approach to wave motion is meant to bring out the underlying similarity between apparently widely differing phenomena. Even our understanding of modern physics, particularly quantum mechanics, depends on clear understanding of this course.

Before coming to wave motion it is essential to understand the physics of oscillations of an isolated body as well as of two or more bodies coupled together. This course is therefore divided into two blocks. Block 1 deals with the study of oscillations of isolated as well as coupled systems. The effect of damping and/or an external harmonic force are discussed here. Block 2 deals with wave motion. The vocabulary of wave motion, reflection, transmission and refraction of waves are discussed in detail. Superposition of waves can give rise to beats, stationary waves, interference or diffraction. These have been discussed with particular emphasis on sound waves.

## Syllabus Per Block Divisions in IGNOU BSc Physics - Oscillations and Waves BPHE-102

### Block 1: Oscillations

**Unit 1:**Simple Harmonic Motion**Unit 2:**Superposition of Simple Harmonic Oscillations**Unit 3:**Damped Harmonic Motion**Unit 4:**Forced Oscillations and Resonance**Unit 5:**Coupled Oscillations

### Block 2: Waves

**Unit 6:**Wave Motion**Unit 7:**Waves at the Boundary of Two Media**Unit 8:**Superposition of Waves -1**Unit 8:**Superposition of Waves -2

**Video:** Simple Harmonic Motion, Coupled Oscillations

**Audio**: Acoustics of Buildings

## Detailed Syllabus for IGNOU BSc Physics - Oscillations and Waves BPHE-102

### Basic Characteristics of Simple Harmonic Motion:

Oscillations of a Spring-Mass System; Differential Equation of SHM and its Solution; Phase of an Oscillator Executing SHM, Velocity and Acceleration; Transformation of Energy in Oscillating Systems: Kinetic and Potential Energies; Calculation of Average Values of Quantities Associated with SHM; Examples of Physical Systems Executing SHM: Simple Pendulum, Compound Pendulum, Torsional Pendulum, LC Circuit; Principle of Superposition; Superposition of Two Collinear Harmonic Oscillations of Same/Different Frequencies; Oscillations in Two Dimensions; Superposition of Two Mutually Perpendicular Harmonic Oscillations of the Same/Different Frequencies; Lissajous Figures.

### Damped and Forced Oscillations:

Differential Equation of a Damped Oscillator and its Solutions, Heavy Damping, Critical Damping, Weak Damping; Characterising Weak Damping: Logarithmic Decrement; Relaxation Time, Quality Factor; Examples of a Weakly Damped System (LCR circuit); Differential Equation of an Undamped Oscillator and its Solution; Differential Equation of a Weakly Damped Forced Harmonic Oscillator and its Solutions, Steady State Solution, Resonance, Examples of Forced Vibrations and Resonance, Power Absorbed by a Forced Oscillator, Quality Factor; An LCR Circuit.

### Basic Concepts of Wave Motion:

Formation of a Wave; Graphical Representation of Wave Motion, Relation between Wave Velocity, Frequency and Wavelength; Mathematical Description of Wave Motion: Phase and Phase Difference, Phase Velocity, Energy Transported by Progressive Waves, Intensity and the Inverse Square Law; One-dimensional Wave Equation: Waves on a Stretched String, Waves in a Field, Waves in a Uniform Rod; Waves in Two and Three Dimensions; The Doppler Effect: Source in Motion and Observer Stationary, Source Stationary and Observer in Motion, Source and Observer both in Motion; Shock Waves.

### Reflection and Refraction of Waves:

The Concept of Wavefront and Huygens’ Construction; Wave Motion and Impedance, Impedance Offered by Strings, Transverse Waves, Impedance Offered by Gases, Sound Waves; Reflection and Transmission; Amplitude Coefficients: Transverse Waves, Longitudinal Waves; Reflection and Transmission Energy Coefficients; Principle of Superposition of Waves; Stationary Waves: Velocity of a Particle at any Point in a Stationary Wave, Harmonics in Stationary Waves; Properties of Stationary Waves; Musical Sound and Noise; Wave Groups and Group Velocity; Beats.