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In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or refracted, when entering a material. This is described by Snell's law of refraction, n1 sin θ1 = n2 ...
Snell's law. Refraction of light at the interface between two media of different refractive indices, with n 2 > n 1. Since the velocity is lower in the second medium (v 2 < v 1), the angle of refraction θ 2 is less than the angle of incidence θ 1; that is, the ray in the higher-index medium is closer to the normal.
Visulization of flux through differential area and solid angle. As always ^ is the unit normal to the incident surface A, = ^, and ^ is a unit vector in the direction of incident flux on the area element, θ is the angle between them.
Fresnel equations. Partial transmission and reflection of a pulse travelling from a low to a high refractive index medium. At near-grazing incidence, media interfaces appear mirror-like especially due to reflection of the s polarization, despite being poor reflectors at normal incidence. Polarized sunglasses block the s polarization, greatly ...
Luminosity is an absolute measure of radiated electromagnetic energy (light) per unit time, and is synonymous with the radiant power emitted by a light-emitting object. [1][2] In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical objects. [3][4] In SI units ...
The speed of light in vacuum is defined to be exactly 299 792 458 m/s (approx. 186,282 miles per second). The fixed value of the speed of light in SI units results from the fact that the metre is now defined in terms of the speed of light. All forms of electromagnetic radiation move at exactly this same speed in vacuum.
Geometrical optics. Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of rays. The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstances. The simplifying assumptions of geometrical optics include that light rays:
Luminous intensity. In photometry, luminous intensity is a measure of the wavelength -weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.