Dispersion


by Krish Beachoo,Christopher Seebaran on Aug 9, 2021

Image: https://unsplash.com/@adam_29063
Edu Level: CSEC,NCSE


What is Dispersion?

The separation of white light (light from the sun) into its component colors.

The component colors:

  • Red
  • Orange
  • Yellow
  • Green
  • Bue
  • Indigo
  • Violet

ROY G BIV

Explanation

BEFORE NEWTON

It had been thought that:

  • Color was a mixture of light and darkness
  • The colors seen was due to impurities in the prism
  • The colors seen was a result of impurities in white in the white light.

NEWTON'S EXPLANATION

Newton's experiment on dispersion prove:

  1. White light is made up of 7 colors, its component colors are:
    • Red
    • Orange
    • Yellow
    • Green
    • Bue
    • Indigo
    • Violet
    • ROY G BIV
  2. The 7 colors can be combined with a 2nd prism to produce the white light.

Physics of the Rainbow

  • A rainbow is formed as a result of total internal reflection by droplets of water in the clouds
  • A higher droplet totally internally reflects and disperse the white light into its component colors
  • Red light from the higher droplet enters our eyes
  • The lower droplets also totally internally reflects and disperses the white light from the sun
  • The droplet refracts the other colors of light into our eyes
  • Note that in a rainbow, the color red appears the highest while violet appears lowest
  • For a rainbow to be seen the sun must be behind the observer


Christopher Seebaran (pc)

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