Find the speed of light of wavelength `lambda =780nm` (in air) in a medium of refractive index `mu=1.55.`
(b) What is the wavelength of this light in the given medium ?

Options

A. `phi_(0) = (1)/(n) ((2 pi)/(lambda_(0))) x`
B. `phi_(0) = n ((2 pi)/(lambda_(0))) x`
C. `phi_(0) = (n - 1) ((2 pi)/(lambda_(0))) x`
D. `phi_(0) = (1)/((n - 1)) ((2 pi)/(lambda_(0))) x`

Answer

b

Explanation

`q phi_(0) = (2 pi)/(lambda_(0)) ("optical path")`
`phi_(0) = (2 pi)/(lambda_(0)) (nx)`