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Reflection of light may be specular (that is, mirror-like) or diffuse (that is, not retaining the image, only the energy) depending on the nature of the interface. Whether the interfaces consists of dielectric-conductor or dielectric-dielectric, the phase of the reflected wave may or may not be inverted.
A mirror provides the most common model for specular light reflection and consists of a glass sheet in front of a metallic coating where the reflection actually occurs. It is also possible for reflection to occur from the surface of transparent media, such as water or glass.
In the diagram, a light ray PO strikes a vertical mirror at point O, and the reflected ray is OQ. By projecting an imaginary line through point O perpendicular to the mirror, known as the normal, we can measure the angle of incidence, θi and the angle of reflection, θr. The law of reflection states that θi = θr, or in other words, the angle of incidence equals the angle of reflection.
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 equationsThe Fresnel equations deduced by Augustin-Jean Fresnel, describe the behaviour of light when moving between media of differing refractive indices. When light moves from a medium of a given refractive index n into a second medium with refractive index n bo, which can be used to predict how much of the light is reflected, and how much is refracted in a given situation. Total internal reflectionTotal internal reflection is an optical phenomenon. When light crosses materials with different refractive indices, the light beam will be bent at the boundary surface (i. refraction). At a certain angle of incidence (the critical angle &theta , the light of light from a denser medium occurs if the angle of incidence is above the critical angleSnell's law is the simple formula used to calculate the refraction of light when travelling between two media of differing refractive index. It is named for its discoverer, Dutch mathematician Willebrord van Roijen Snell ( 1580- 1626). Overview Refraction.
For parabolic reflection, such as those used in car headlights, see paraboloidIn mathematics, a paraboloid is a quadric, a type of surface in three dimensions, described by the equation: : (elliptic paraboloid), or : (hyperbolic paraboloid). Hyperbolic paraboloid. There are two kinds of paraboloid: elliptic and hyperbolic. The elli.
==Other types of reflection==
Light bounces off in all directions due to the microscopic irregularities of the interface; this is an omnipresent phenomenon, applicable for all non-shiny objects that are not black.