Lloyd’s Single mirror

When a light wave passes from a rarer medium to a denser medium, there will be a phase change of pi radians. This difference brings change in the conditions for constructive and destructive interference. This phenomena also reasons the fromation of interference pattern in thin films like, oily layer, soap film, etc., but has no reason on the shifting of fringes from the central portion outward. The shift is dependent on the refractive index of the material as per the relation, Delta y = (mu - 1) t The condition for constructive interference in Lloyd's single mirror experiment is the path difference which is equal to

______ mirror is used as shaving mirror.

Lloyds mirror experiment