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.
The refractive index is maximum for violet colour of light and minimum for red colour of light. i.e., μv > μ R therefore critical angle is maximum for red colour of light and minimum for violet colour of light, i.e., Cv < CR
Total internal reflection occurs if angle of incidence in denser medium exceeds critical angle.
Mirage is an optical illusion observed in deserts and roads on a hot day when the air near the ground is holler and hence rarer than the air above.