Consider a ray of light incident from air onto a slab of glass (refractive index n) of width d, at an angle `theta` . The phase difference between the ray reflected by the top surface of the glass and the bottom surface is
A. `(4pi d)/(lambda)(1-(1)/(n^(2))"sin"^(2)theta)^(1//2)+pi`
B. `(4pi d)/(lambda)(1-(1)/(n^(2))"sin"^(2)theta)^(1//2)`
C. `(4pi d)/(lambda)(1-(1)/(n^(2))"sin"^(2)theta)^(1//2)+(pi)/(2)`
D. `(4pi d)/(lambda)(1-(1)/(n^(2))"sin"^(2)theta)^(1//2)+2pi`
