A beam of light is reflected from a smooth surface, such as a mirror, in a single beam which makes the same angle with the normal as the incident beam (specular reflection).
Light is scattered in all directions from an uneven surface.
Light is refracted at the boundary between glass (and water and Perspex) and air; this property is exploited in prisms and lenses.
When a beam of white light is passed through a prism, the emerging light beam is spread out showing the colours of the spectrum.
This can be explained using the wave model, different colours have different wavelengths; different wavelengths travel at different speeds when passing through glass, water or Perspex.
What we perceive as white light is a mixture of different colours, ranging in wavelength from violet light (shortest visible wavelength) to red light (longest visible wavelength).
A coloured filter works by allowing light of one or more wavelength through (transmission) and absorbing light of the other wavelengths.
An object appears white if it scatters all the colours of light that fall on it, and black if it scatters none (and absorbs all).
It appears coloured if it scatters light of some colours and absorbs light of other colours. Its observed colour is that of the light it scatters. |