Lecture Notes: Reflection of Waves

Introduction

• Focus on how waves can be reflected off a boundary
• Discussion includes ray diagrams and types of reflection: specular and diffuse

Wave Behavior at Boundaries

• When a wave arrives at a boundary between two materials, three outcomes are possible:
  1. Absorption: Wave energy is transferred to the material's energy stores.
  2. Transmission: Wave enters and passes through the material, often leading to refraction.
  3. Reflection: Wave bounces off the surface and does not enter the material.
• The outcome depends on the wave's wavelength and the properties of the materials involved.

Ray Diagrams

• Used to demonstrate reflection
• Angle of Incidence = Angle of Reflection

Steps to Draw a Ray Diagram

1. Identify the boundary between two materials (e.g., air and a mirror).
2. Draw the incoming ray of light with an arrow indicating direction towards the mirror.
3. Draw the normal line, which is perpendicular (90 degrees) to the surface at the point of incidence.
4. Measure the angle of incidence between the incoming ray and the normal.
5. According to the rule, draw the reflected ray at the same angle from the normal.
6. The point where the incoming ray touches the boundary is called the point of incidence.

Types of Reflection

Specular Reflection

• Occurs on smooth surfaces like mirrors.
• Normals are uniform, leading to light being reflected in the same direction.
• Produces a clear image (e.g., a mirror).

Diffuse or Scattered Reflection

• Occurs on rough surfaces like paper.
• Normals point in various directions due to surface irregularities.
• Light is reflected in different directions, preventing clear image formation.
• Despite surface roughness, angle of incidence = angle of reflection.

Conclusion

• Summary of key points on reflection and types of reflection.
• Encouragement to share the learning with others.