A ray of light travels from a medium of refractive index `mu` to air. Its angle of incidence in the medium is `i` and its angle of deviation is `delta`. (a) What is the angle of deviation for `i lt C` and `i gt C`, where Ci s the critical angle. (b) Plot a curve between angle of deviation `delta` versus angle of incidence `i`.

Explanation

(a) `ileC`

`sinC=1//mu`
`musini=1xxsinrimpliesr=sin^-1(musini)`
Angle of deviation
`delta=r-i`
`=sin^-1(musini)-i`
When `i=C`,
`delta=sin^-1(musini)-C`
`=sin^-1(1)-C`
`pi/2-C`
(b) `igeC`

`delta=180^@-2i=pi-2i`
When `i=C`, `delta=pi-2C`
`i=pi//2`, `delta=0`
`delta v/s i` graph will be straight line with `-ve` slope
`delta v//s i` graph