6.3.4 Visible Light Spectrum

Visible Light (Physics only)

• Blue has a shorter wavelength and higher frequency than red.
• Sunlight is a mix of all colours, and this mix appears white (i.e., white light is normal light).

Types of Reflection

• Specular:
  • A smooth surface gives a single reflection.
• Diffuse:
  • Reflection off a rough surface causes scattering.

Colour Filters

• This works by the filter absorbing every other colour.
  • Only letting certain wavelengths (i.e., a certain colour) through.

Opaque Colours

• An opaque object has colour, determined by the strength of reflection for different wavelengths.
  • Wavelengths which are not reflected are absorbed:
  • If all wavelengths reflect, it is white in colour.
  • If all wavelengths are absorbed, it appears black.
  • The wavelength which is absorbed = the colour in which it appears.