An air bubble in a glass slab with refractive index `1.5` (near normal incidence) is `5 cm` deep when viewed from one surface and `3cm` deep when viewed from the opposite face. The thickness (in `cm)` of the slab is

Options

A. 8
B. 10
C. 12
D. 16

Answer

C

Explanation

(c ) Let thickness of the given slab is t. According to the question, when viewed from both the surfaces

`rArrx/mu+(t-x)/mu=3+5rArrt/mu=8 cm`
`therefore` Thickness of the slab,`t=8xxmu=8xx3/2=12 cm`