The phenomena of light involved in the formation of a rainbow are refraction, dispersion, and internal (total internal) reflection.

Quick Scoop

  • Sunlight enters tiny raindrops and refracts (bends) at the air–water surface.
  • Inside the drop, the different colours of white light spread out – this is dispersion.
  • The light then undergoes internal reflection from the back surface of the drop and is sent back toward the observer.
  • As it leaves the drop, it refracts again, making the separated colours visible as a rainbow.

So, if this is a multiple-choice question, the correct option is the one that lists: dispersion, refraction and internal reflection of light.

Bonus fact: In a primary rainbow, red appears on the top (outer side) and violet at the bottom (inner side).

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