 Plane of incidence

For a ray meeting an interface at nonzero incidence angle, the plane spanned by the incoming wavevector and the surface normal. transverse electric polarization has electric field perpendicular to this plane, while transverse magnetic polarization has electric field in it. At exact normal incidence, the surface normal and ray alone do not select a unique plane.

The plane of incidence is an important concept in optics, particularly in the study of reflection and refraction of light. It refers to the geometric plane defined by three key elements: 1. The incident ray: The incoming light ray that strikes a surface (such as a mirror or a boundary between two media). 2. The normal line: The perpendicular line to the surface at the point of incidence. This line is crucial for analyzing the angles of incidence and reflection.