Cauchy’ s Formula
Critical Angle
The angle of incidence in a denser medium for which the angle of refraction in rarer medium becomes 90 °. is called critical angle( C).
Critical angle for diamond = 24 ° Critical angle for glass = 42 °: Critical angle for water = 48 °:
Refractive index of denser medium μ = 1 / sin C
Total Internal Reflection( TIR)
When a light ray travelling from a denser medium towards a rarer medium is incident at the interface at an angle of incidence greater than critical angle, then light rays reflected back in to the denser medium. This phenomena is called TIR.
Critical angle increases with temperature.