Reflection (physics)

Reflection of light

Reflection of light can be either specular (mirror-like) or diffuse (retaining energy but losing the image).
Specular reflection occurs at the surface of a mirror or transparent media like water or glass.
The angle of incidence equals the angle of reflection, according to the law of reflection.
Reflection can occur when light travels from a medium with one refractive index to a medium with a different refractive index.
Total internal reflection occurs when the angle of incidence is greater than the critical angle, and it is used in applications like X-ray telescopes.

Specular reflection occurs when the reflecting surface is very smooth.
The incident ray, reflected ray, and normal to the reflection surface lie in the same plane.
The angle of incidence is equal to the angle of reflection.
The reflected ray and the incident ray are on opposite sides of the normal.
These laws can be derived from the Fresnel equations.

Diffuse reflection occurs when light strikes the surface of a non-metallic material and bounces off in all directions.
It is caused by multiple reflections by microscopic irregularities inside the material and on its surface.
The exact form of diffuse reflection depends on the structure of the material.
Lambertian reflectance is a common model for diffuse reflection, where light is reflected with equal luminance or radiance in all directions.
Diffuse reflection is the primary mechanism of physical observation for most objects we see.

Retroreflection is a phenomenon where light is returned in the direction from which it came.
Some surfaces exhibit retroreflection, such as those with curved droplets or corner reflectors.
Retroreflection can be seen when flying over clouds or with dew on grass.
Animals like cats and dogs have retinas that act as retroreflectors, improving their night vision.
Retroreflective surfaces can be created using mirrors or by depositing refractive spheres or pyramid-like structures.

In classical electrodynamics, light is considered as an electromagnetic wave described by Maxwell's equations.
Light waves induce small oscillations of polarization in atoms or electrons, causing each particle to radiate a small secondary wave.
The combination of these secondary waves gives rise to specular reflection and refraction.
In dielectrics like glass, the electric field of light acts on electrons, generating forward and backward radiation that contributes to refraction and reflection.
In metals, free electrons oscillate with incident light, resulting in cancellation of forward radiation and reflection of backward radiation.

Light reflects off a mirror, creating one image.
Two mirrors placed face to face produce an infinite number of images along a straight line.
Multiple images between two mirrors at an angle lie over a circle.
Four mirrors placed face to face create an infinite number of images in a plane.
Multiple images between four mirrors forming a pyramid lie over a sphere.

Phase conjugation causes light to bounce back in the opposite direction.
Wavefronts are reversed in complex conjugate reflection.
Conjugate reflectors can remove aberrations from a beam.
Looking into a complex conjugating mirror would appear black.
Only photons that left the pupil would reach the pupil in a complex conjugating mirror.

Neutron reflection
Beryllium and other materials reflect neutrons.
Neutron reflection is used in nuclear reactors and weapons.
Reflection of neutrons off atoms helps determine internal structure in science.
Sound reflection
Longitudinal sound waves reflect in a coherent manner on a flat surface.
Reflection of sound depends on the texture and structure of the surface.
Porous materials absorb some sound energy.
Rough surfaces scatter sound energy in many directions.
Sound reflection affects the acoustic space and is important in architectural acoustics.
Seismic reflection
Seismic waves produced by earthquakes are reflected by layers within the Earth.
Reflection seismology uses shallow reflections to study the Earth's crust and prospect for petroleum and gas deposits.
Deep reflections of earthquake waves help determine the layered structure of the Earth.
Seismic reflection has contributed to understanding the Earth's composition.
Reflection seismology is used in oil and gas exploration.

Reference	URL
Glossary	https://harryandcojewellery.com.au/blogs/glossary/reflection-physics
Wikipedia	http://en.wikipedia.org/wiki/Reflection_(physics)
Wikidata	https://www.wikidata.org/wiki/Q165939
Knowledge Graph	https://www.google.com/search?kgmid=/m/02l215