CIE IGCSE Physics

Revision Notes

3.2.5 Dispersion of Light

What is Dispersion of Light?

  • When light enters a denser medium, such as glass, it slows down (refracts), which causes it to bend
  • Different colours, however, slow down by different amounts, which causes them to bend by different amounts
  • This effect is known as dispersion and can be used to separate white light into its individual colours

refraction-by-prism, IGCSE & GCSE Physics revision notesWhen white light is shone through a prism it is dispersed into its individual colours

  • The seven colours of the spectrum are:

Light Spectrum, IGCSE & GCSE Physics revision notes

Red, Orange, Yellow, Green, Blue, Indigo, Violet

  • You can remember these colours either by remember the name:
Roy G. Biv
  • Or by remembering the phrase:
Richard Of York Gave Battle In Vain
Extended Only

Light as a Wavelength

  • Light is a transverse wave
  • The different colours of light all have different wavelengths (and frequencies)
    • Red has the largest wavelength
    • Violet has the shortest wavelength
  • Light of a single wavelength (a single colour) is known as monochromatic

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