Map convert, ' cd ', ' lm ', ' cd ' ' m ' 2, ' lx ', ' dimensions ', ' base ' = true Ī footcandle is defined as a lumen per square foot. Īn apostilb is defined as 0.0001 lambert. Ī footlambert is defined as 1 π candela per square foot. Ī lambert is defined as 1 π candela per square centimeter. Ī stilb is defined as a candela per square centimeter. Ī nit is defined as a candela per square meter. The only unit of luminous flux is the lumen. The units of light are defined as follows.Ī Hefner unit is approximately 0.903 candela. Refer to a unit in the Units package by indexing the name or symbol with the context, for example, candela or lx or, if the context is indicated as the default, by using only the unit name or symbol, for example, candela or lx. Maple knows the units of light listed in the following table.Īn asterisk ( * ) indicates the default context, an at sign indicates an abbreviation, and under the prefixes column, SI indicates that the unit takes all SI prefixes, IEC indicates that the unit takes IEC prefixes, and SI+ and SI- indicate that the unit takes only positive and negative SI prefixes, respectively. The SI unit of illuminance is the lux, which is defined as a candela steradian per square meter. Illuminance has the dimension luminous intensity solid angle per length squared. The SI composite unit of luminous luminance is the candela per meter squared. Luminous luminance has the dimension luminous intensity per length squared. The SI unit of luminous flux is the lumen, which is defined as a candela steradian. Luminous flux has the dimension luminous intensity solid angle. The SI unit of luminous intensity is the candela, which is defined as the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 5.4 × 10 14 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian (16th CGPM, 1979). "The International System of Units (SI)." NIST Special Publication 330, 1991 Edition.Luminous intensity is a base dimension in the International System of Units. "Guide for the Use of the International System of Units (SI)." NIST Special Publication 811, 1995 Edition. "The International Bureau of Weights and Measures 1875-1975." NBS Special Publication 420, 1975 Edition. National Institute of Standards and Technology. "Conversion of Equations and Amounts between SI Units and Gaussian Units."Īppendix §4 in Classical Electrodynamics, 3rd ed. Standard for the Use of the International System of Units (SI): The Modern Metric System. "The International System of Units (SI), 7th ed." 1998.īureau International des Poids et Mesures. īureau International des Poids et Mesures. "The International System of Units (SI).". Superseded by IEEE/ASTM SI10-1997.īureau International des Poids et Mesures. The seven fundamental units are summarized in the following table.ĪSTM. The current version of the SI was completed by adding the mole as base unit for amount of substance, bringing the The name International System of Units (SI) was given to the system by the 11th CGPM in 1960. The volt will probably replace the ohm further in the future when measurements using Josephson However, the ampere is scheduled to be phased out as a base unit in the nearįuture in favor of the ohm, which can be measured extremely accurately using the quantum Hall effect. Kelvin, and candela as base units for electric current, thermodynamic temperature, and The 10th Conférence Générale des Poids et Mesures (CGPM) approved the introduction of the ampere, This proposal was approved by the Comité International des Poids et Mesures (CIPM) in 1946.įollowing an international inquiry by the Bureau International des Poids et Mesures (BIPM), which began in 1948, in 1954 The SI units are sometimes also known as MKS units, where MKS stands for "meter, kilogram, and second." Inġ939, the CCE recommended the adoption of a system of units based on the meter, kilogram, second,Īnd ampere. "SI" stands for "System International" and is the set of physical units agreed upon by international convention. Portions of this entry contributed by Dana Romero SI - from Eric Weisstein's World of Physics
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