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)[(sin506^(@))/(1.5)]-50^(@)`

Answer

B

Explanation

`""^(a)mu_(g)=1.5`
`therefore1.5="cosec C" or C=42^(@)`. Crtical angle for glass `=42^(@)`. Hence a ray of light incident at `50^(@)` in glass medium undergoes total internal reflection. `delta` denotes the dev I ation of the ray.
`therefore delta =180^(@)-(50^(@)+50^(@)) or delta=80^(@)`