A ray of light is travelling from glass to air (Refractive index of glass = 1.5).The angle of incidence is `50^(@)`.The deviation of the ray is

Options

A. `0^(@)`
B. `80^(@)`
C. `50^(@) - sin^(-1)[(sin50^(@))/(1.5)]`
D. `sin^(-1)[(sin50^(@))/(1.5)]-50^(@)`

Answer

B

Explanation

`.^(a)mu_(g) = 1.5`
`therefore 1.5` = cosec C or `C = 42^(@)`
Critical angle for glass = `42^(@)`. Hence a ray of light incident at `50^(@)` in glass medium undergoes total internal reflection. `delta` denotes the deviation of the ray.
`therefore delta = 180^(@)` - `(50^(@) + 50^(@))` or `delta = 80^(@)`