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. 16
B. 8
C. 10
D. 12

Answer

D

Explanation

`H_(app) = (H_(R ) )/(mu_(g)) rArr H_(R ) = mu_(g) H_(qpp)`
So, `H_(R_(1)) = mu_(g) H_(app1) " and " H_(R_(2)) = mu_(g) H_(app2)`
So, thickness = `H_(R_(1)) + H_(R_(2))`
`= mu_(g) [H_(app1) + H_(app2) ] = (3)/(2) [ 5 + 3] = (3)/(2) xx 8 = 12 ` cm