OPTICAL PHENOMENA

Reflection

Reflection of light is either specular  or diffuse depending on the nature of the interface.Furthermore, if the interface is between a
dielectric and a conductor,the phase of the reflected wave is retained, otherwise if the interface
is between two dielectrics, the phase may be retained or inverted, depending on the induces of
refraction.

A mirror provides the most common model for specular light reflection,and typically consists of a glass.sheet with a metallic coating where the reflection actually occurs.Reflection is enhanced in metals by.suppression of wave propagation beyond their skin depths. Reflection also occurs at the surface of.transparent media,such as water or glass.

                                 In fact,reflection of light may occur whenever light travels from a medium of a given refractive.index into a medium with a different refractive index.In the most general case,a certain fraction of the light is reflected from the interface,and the remainder is refracted.Solving Maxwell's equations for a light ray striking a boundary allows the derivation of the Fresnel equations,which can be used to predict how much of the light reflected, and how much is refracted in a given situation. Total internal reflection of light from a denser medium occurs if the angle of incidence is above the critical angle.

When light reflects off a material denser (with higher refractive index) than the external medium, it undergoes a polarity inversion. In contrast, a less dense, lower refractive index material will reflect light in phase. This is an important principle in the field of thin-film optics.