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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 ... more

The beta angle is a measurement that is used most notably in spaceflight. The beta angle determines the percentage of time an object such as a spacecraft ... more

In chemistry, a closely related quantity called “absorbance” or “decadic absorbance” is used instead of optical depth: the common ... more

Security characteristic line (SCL) is a regression line, plotting performance of a particular security or portfolio against that ... more

Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by ... more

The Penman equation describes evaporation (E) from an open water surface, and was developed by Howard Penman in 1948. Penman’s equation requires ... more

In optics, a Gaussian beam is a beam of electromagnetic radiation whose transverse electric field and intensity (irradiance) distributions are well ... more

Attenuation coefficient or narrow beam attenuation coefficient of the volume of a material characterizes how easily it can be penetrated by a beam of ... more

black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A black hole ... more

Albedo (/ælˈbiːdoʊ/), or reflection coefficient, derived from Latin albedo “whiteness” (or reflected sunlight) in turn from albus ... more