A ray of light is incident normally on a glass slab of thickness 5 cm and refractive index 1.6. The time taken to travel by a ray from source to surface of slab is same as to travel through glass slab. The distance of source from the surface is

Options

A. 4 cm
B. 8 cm
C. 12 cm
D. 16 cm

Answer

B

Explanation

Data
`d_(g) =5 cm, mu_(g) =1.6 t_(a) =t_(g), d_(a) =?`
`(d_(a))/(v_(a))=(d_(g))/(v_(g))" "therefore d_(a) =(v_(a))/(v_(g))d_(g) =mu_(g) . d_(g)`
`d _(a) =1.6 xx5=8 cm`