Two light waves having the same wavelength `lambda` in vacuum are in phase initially. Then the first ray travels a path of length `L_(1)` through a medium of refractive index `mu_(1)`. Then second ray travels a path of length `L_(2)` throug a medium of refractive index `mu_(2)`. The two waves are then combined to observed interference effects. The phase difference between the two, when they interfere, is

Options

A. `(2pi)/(lambda) (n_2L_1 - n_1 L_2)`
B. `(2pi)/(lambda) (n_1 L_1 - n_2 L_2)`
C. `(2pi)/(lambda) ((L_2)/(n_1) - (L_1)/(n_2))`
D. `(2pi)/(lambda) ((L_(1))/(n_(1)) - (L_(2))/(n_(2)))`