Question

A light beam is traveling from Region I to region IV (refer figure). The refractive indices in Region I, II, III, and IV are `n_(0), n_(0)//2,n_(0)//6 and n_(0)//8` , respectively. The angle of incidence `theta` for which the beam just misses entering Region IV is

A. `sin^(-1).((3)/(4))`
B. `sin^(-1).((1)/(8))`
C. `sin^(-1).((1)/(4))`
D. `sin^(-1).((1)/(3))`

Answer 1

Correct Answer - B
`n_(0) "sin"theta = ((n_(0))/(8)) "sin"90^(@) implies "sin" theta = (1)/(8) implies theta = sin^(-1).((1)/(8))`