Calculate the critical angle for glass air surface if a ray of light which is nicident ni air on the glass surface is deviated through `15^(@)`, when the angle of incidence is `45^(@)`.

Answer

`45^(@)`

Explanation

Here, `I = 45^(@), r = 45^(@) - 15^(@) = 30^(@)`
`mu = (sin i)/(sin r) = (sin 45^(@))/(sin 30^(@)) = (1)/(sqrt(2)) xx 2 = sqrt(2)`
`sin C = (1)/(mu) = (1)/(sqrt(2)) :. C = 45^(@)`