In describing reflection and

refraction In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomen ...

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultra ...

, the plane of incidence (also called the incidence plane or the meridional plane) is the plane which contains the

surface normal In geometry, a normal is an object such as a line, ray, or vector that is perpendicular to a given object. For example, the normal line to a plane curve at a given point is the (infinite) line perpendicular to the tangent line to the curve ...

and the propagation vector of the incoming radiation. (In wave optics, the latter is the k-vector, or wavevector, of the incoming wave.) When reflection is specular, as it is for a mirror or other shiny surface, the reflected ray also lies in the plane of incidence; when

also occurs, the refracted ray lies in the same plane. The condition of co-planarity among incident ray, surface normal, and reflected ray (refracted ray) is known as the first law of reflection (first law of refraction, respectively).

Polarizations

{{main, Polarization (waves)#s and p{{!''s'' and ''p'' polarizations The orientation of the incident light's

polarization Polarization or polarisation may refer to: Mathematics *Polarization of an Abelian variety, in the mathematics of complex manifolds *Polarization of an algebraic form, a technique for expressing a homogeneous polynomial in a simpler fashion by ...

with respect to the plane of incidence has an important effect on the strength of the reflection. ''P-polarized'' light is incident

linearly polarized In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation. The term ''linear polarizati ...

light with polarization direction lying in the plane of incidence. ''S-polarized'' light has polarization perpendicular to the plane of incidence. The ''s'' in s-polarized comes from the German word ''senkrecht'', meaning perpendicular. The strength of reflection from a surface is determined by the

Fresnel equations The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light (or electromagnetic radiation in general) when incident on an interface between different optical media. They were deduced by Augustin-Jean Fr ...

, which are different for s- and p-polarized light.

References

Geometrical optics

Polarizations

See also

References