A ray of light `(R_(1))` is incident on a glass slab at an angle equal to critical angle of glass - air system. The refracted ray `(R_(2))` undergoes partial reflection and refraction at other surface of slab. The angle between the reflected ray `(R_(3))` and refracted ray `(R_(4))` is

Options

A. `45^(@)`
B. `135^(@)`
C. `105^(@)`
D. `75^(@)`

Answer

C

Explanation

From Snell's law `sqrt(2)"sin"I = 1 "sin"90^(@)`

`I'= 45^(@)`
`therefore "Again 1 . "sin"45^(@) = sqrt(2)"sin"r`
`r= 30^(@)` & `sqrt(2)"sin"30^(@) = 1 "sin"r'`
`r'= 45^(@)`
Hence `theta = 180^(@) - (30+45^(@)) = 105^(@)`