ISO Units.
Seven Base & Twenty-two Derived.
Seven Base & Twenty-two Derived.
Time is the indefinite continued progress of existence and events in the past, present, and future regarded as a whole.
It is measure in seconds, a unit of time derived from:
In the SI system, the rigourous definition of a second is given
from the fixed numerical value of the caesium 133 atom's transition frequency, ΔνCs,
(unperturbed, ground-state hyperfine)
which is 9192631770 Hz with 1 Hz = 1 / s.
The numerical measurement of how far apart objects are. Distance or length is sometimes metaphorical, e.g. the "manhattan distance" a measure of distance between two points defined as the sum of absolute differences of their respective Cartesian coordinates. Distances in SI system are expressed in metres. A metre is defined as the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second.
An intrinsic property of a body. It is expressed in kilograms, where the Planck constant is h = 6.62607015 x 10-34 kg.m2.s-1. This constant combined with prior definitions of a second and a meter, gives the definition of a kilogram.
The ampere is the SI unit of electric current, where one is equal to 1 coulomb moving past a point per second, where a coulomb is defined from the elementary charge, at the proportion e = 1.602176634 x 10-19 C
The kelvin unit is defined by taking the Boltzmann constant k, to be 1.380 649 x 10-23 when expressed in the unit J.K-1, which is equivalent kg.m2.s-2.K-1.
A mole is exactly 6.02214076 x 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA.
A candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation
of frequency 540 x 1012 Hz,
that has a radiant intensity in that direction of 1/683 watt per steradian.