A glass of refractive index 1.5 is coated with a thin layer of thickness of |
A glass of refractive index 1.5 is coated with a thin layer of thickness of |
(90)
Path difference between rays reflected from upper and lower faces of layer (for normal incidence). But there is abrupt change in path of
of light at upper surface. So actual path difference is
For constructive interference
. For least thickness