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

Here `mu=1.5`
l=length of the slab
x=position of air bubble from one side

As per question, total apparent length of slab `=5+3`
or `(x)/(mu)+((l-x))/(mu)=8 "or" (l)/(mu)=8`
`:.l=8mu=8xx1.5=12cm`