Class 10 Physics Human Eye and Colourful World Refraction through a triangular prism

Refraction through a triangular prism




  • The above figure shows a triangular prism with 2 triangular bases and 3 lateral rectangular surfaces.
  • The surfaces are inclined at an angle of 60 degrees to each other.
  • This is called the 'Angle of the prism'




  • When a ray of light moves from one surface to another it bends. This is called Refraction
  • The ray of light from air is incident on the glass surface AB. On hitting the surface AB, it bends towards the normal.
  • At the surface AC, the light ray moves from glass to air. It again bends.
  • T he angle of incidence (i), the angle of refraction (r) and the angle of emergence (e) is as shown in the figure.
  • PQ is the incident ray
  • QR is the refracted ray
  • RS is the emergent ray.

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