Colour of objects

A material gets its colour as electrons absorb some wavelengths of light and reflect others. The colour an observer sees corresponds with the reflected wavelengths.

  • Three key factors affect the colour of an object:
    • The light source and what happens to the light on its journey towards an object.
    • What happens when light strikes a material or medium.
    • Factors related to an observer that affect the way they perceive things.

A material gets its colour as electrons absorb some wavelengths of light and reflect others. The colour an observer sees corresponds with the reflected wavelengths.

About chromophores
  • Things appear to have colour because they absorb some wavelengths of light and reflect others.
  • Chromophores are the part of molecules responsible for the absorption and reflection of light.
  • A chromophore is formed by a group of atoms within a molecule and the electrons that orbit their nuclei.
  • The colour produced by an opaque object corresponds with the wavelengths not absorbed during the interaction of light with the chromophores of the molecules that form its surface.
  • Whether different wavelengths of light are absorbed or reflected by a chromophore depends on whether there is an energy difference between orbiting electrons.
  • If the energy difference between the electrons of a chromophore falls within the range of the visible spectrum (2 to 2.75 electron volts) then it produces the colour seen by an observer.
Related diagrams

Each diagram below can be viewed on its own page with a full explanation.

References