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Water is amphoteric: it has the ability to act as either an acid or a base in chemical reactions. [87] According to the Brønsted-Lowry definition, an acid is a proton (H +) donor and a base is a proton acceptor. [88] When reacting with a stronger acid, water acts as a base; when reacting with a stronger base, it acts as an acid. [88]
Luminosity is an absolute measure of radiated electromagnetic energy 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]
Water is an inorganic compound with the chemical formula H 2 O.It is a transparent, tasteless, odorless, [c] and nearly colorless chemical substance.It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent [20]).
Prior to the definition of the candela, a variety of units for luminous intensity were used in various countries. These were typically based on the brightness of the flame from a "standard candle" of defined composition, or the brightness of an incandescent filament of specific design.
International Association for the Properties of Water and Steam; Ioffe institute, Russian Federation; Crystran, United Kingdom; Jena University, Germany; Hyperphysics list of refractive indices; Luxpop: Index of refraction values and photonics calculations; Kaye and Laby Online Provided by the National Physical Laboratory, UK
The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. The study of chemical structure by means of energy absorption and release is generally referred to as spectroscopy.
Several measures of light are commonly known as intensity: . Radiant intensity, a radiometric quantity measured in watts per steradian (W/sr); Luminous intensity, a photometric quantity measured in lumens per steradian (lm/sr), or candela (cd)
The directional reflectance of a surface, denoted R Ω, is defined as [1] =,,, where . L e,Ω r is the radiance reflected by that surface;; L e,Ω i is the radiance received by that surface.