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Dispersion of Light

Key TermMeaning
DispersionSplitting of white light into different colours when it passes through a prism.
White LightMixture of many wavelengths (many colours).
Monochromatic LightLight consisting of a single wavelength (one colour), e.g. laser light.
Why Dispersion HappensDifferent wavelengths travel at different speeds in glass and refract by different amounts.
Colour BendingRed bends least (longest wavelength). Violet bends most (shortest wavelength).
Visible Spectrum OrderMemory Aid
Red → Orange → Yellow → Green → Blue → Indigo → VioletROYGBIV

Exam Tip: When explaining dispersion, mention wavelengths, different speeds in glass, and different angles of refraction.

  • Light entering a denser medium bends towards the normal.
  • Light entering a less dense medium bends away from the normal.
  • The frequency stays constant.
  • The wavelength changes.