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

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

`rArr " " (x)/(mu)+(t-x)/(mu)=3+5 rArr (t)/(mu)=8 cm`
`rArr` Thickness of the slab, `t=8xx mu=8xx(3)/(2)=12 cm`