Dispersion of Light (Cambridge (CIE) IGCSE Physics)

Dispersion of light

• The dispersion of light is illustrated by the refraction of white light by a glass prism

• White light contains the wavelengths of all the colours of the spectrum

  • Each colour has a different wavelength (and frequency), making up a very narrow part of the electromagnetic spectrum

• White light may be separated into all its colours by passing it through a glass prism

  • This is done by refraction

  • Violet light is refracted the most, whilst red light is refracted the least

  • This splits up the colours to form a spectrum

• This process is similar to how a rainbow is created

Dispersion of light through a prism

White light may be separated into all its colours by passing it through a prism

The visible spectrum of light

• Visible light is the only part of the spectrum detectable by the human eye

  • In the natural world, many animals, such as birds, bees and certain fish, can perceive beyond visible light and can see infra-red and UV wavelengths of light

• The seven different colours of visible light waves correspond to different wavelengths

• In order of longest wavelength and lowest frequency to shortest wavelength and highest frequency :

  • Red 

  • Orange

  • Yellow

  • Green 

  • Blue

  • Indigo

  • Violet

The dispersion of light creates the seven colours of the visible spectrum

The colours of the visible spectrum: red has the longest wavelength; violet has the shortest

Monochromatic light

Extended tier only

• A visible light source of a single frequency (a single colour) is monochromatic

• A laser beam is monochromatic because it emits a single colour of light

A laser beam

The laser emits monochromatic green light