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The SI has special names for 22 of these coherent derived units (for example, hertz, the SI unit of measurement of frequency), but the rest merely reflect their derivation: for example, the square metre (m 2), the SI derived unit of area; and the kilogram per cubic metre (kg/m 3 or kg⋅m −3), the SI derived unit of density. The names of SI ...
The steradian (symbol: sr) or square radian[ 1][ 2] is the unit of solid angle in the International System of Units (SI). It is used in three dimensional geometry, and is analogous to the radian, which quantifies planar angles. A solid angle in steradians, projected onto a sphere, gives the area of a spherical cap on the surface, whereas an ...
The unit was formerly an SI supplementary unit and is currently a dimensionless SI derived unit, [2] defined in the SI as 1 rad = 1 [3] and expressed in terms of the SI base unit metre (m) as rad = m/m. [4] Angles without explicitly specified units are generally assumed to be measured in radians, especially in mathematical writing. [5]
The International System of Units, internationally known by the abbreviation SI (from French Système international d'unités ), is the modern form of the metric system and the world's most widely used system of measurement. Coordinated by the International Bureau of Weights and Measures (abbreviated BIPM from French: Bureau international des ...
the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle. degree (°) ∠ BAC. extensive, scalar. Luminous intensity. Iv. Wavelength - weighted power of emitted light per unit solid angle. candela (cd) J.
The current international standard for the metric system is the International System of Units (Système international d'unités or SI). It is a system in which all units can be expressed in terms of seven units. The units that serve as the SI base units are the metre, kilogram, second, ampere, kelvin, mole, and candela.
The SI system after 1983, but before the 2019 redefinition: Dependence of base unit definitions on other base units (for example, the metre is defined as the distance travelled by light in a specific fraction of a second), with the constants of nature and artefacts used to define them (such as the mass of the IPK for the kilogram).
This list of international units is subsidiary to the list of units article and lists widely used modern units in a form of sortable table. The duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. 299 792 458 second.