A light beam is travelling from Region I to Region IV (Refer Figure). The refractive index in Regions 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

Options

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

Answer

`sin^-1 (frac(1)(3))`