Reflection

$All waves can be absorbed, transmitted or reflected$

When waves arrive at a boundary between two different materials, three things can happen:

• The waves are absorbed by the material the wave is trying to cross into-this transfers energy to the material’s energy stores
• The waves are transmitted-the waves carry on travelling through the new material, which often leads to refraction
• The waves are reflected

  What actually happens depends on the wavelength of the wave and the properties if the materials involved

\ $You can draw a simple ray diagram for reflection$

• There’s one simple rule to learn for all reflected waves:

  Angle of incidence = Angle of reflection

• The angle of incidence is the angle between the incoming wave and normal
• The angle of reflection is the angle between the reflected wave and the normal
• The normal is an imaginary line that’s perpendicular to the surface at the point of incidence

  The normal is usually shown as a dotted line

\ $Reflection can be specular or diffuse$

• Waves are reflected at different boundaries in different ways
• Specular reflection happens when a wave is reflected in a single direction by a smooth surface
• Diffuse reflection us when a wave is reflected by a rough surface and the reflected rays are scattered in lots of different directions
• This happens because the normal is different for each incoming ray, which means that the angle of incidence for each ray. The rule of angle of incidence = angle of reflection still applies
• When light is reflected by a rough surface, the surface appears matte and you don’t get a clear refection of objects

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