Reflection

• Reflection - when a wave bounces off a boundary.
• Things that can happen when a wave meets a boundary;

  • Absorbed - energy from wave is transferred to material's energy store.
  • Transmitted - enters material but carries on travelling (often leads to refraction).
  • Reflected
• What happens to to wave when it meets a boundary depends on its wavelength and properties of the two materials.
• In reflection the angle of incident is equal to the angle of reflection.
• Ray diagram of reflection;

  A) Incident ray

  B) Reflected ray

  C) Normal

  D) Angle of incidence

  E) Angle of reflection

  
• Types of reflection:

  • Specular reflection
  • Diffuse / Scattered reflection
• Specular reflection;

  • Happens only when the boundary is flat.
  • As the boundary is flat then the normal is in the same direction everywhere.
  • SO all light rays are reflected in the same direction,
  • They create a clear image.
  • Example is a mirror.
• Diffuse/Scattered reflection;

  • Happens when boundary is bumpy.
  • As boundary is bumpy then all the normals will be different.
  • This means that the light will be reflected in different directions.
  • It doesn't create a clear image.
  • Example is paper.