quantity

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property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed by means of a number and a reference. for example a measure with a unit.

Quantities can appear as base quantities or derived quantities.

EXAMPLE 1 Length, mass, electric current (ISQ base quantities).
EXAMPLE 2 Plane angle, force, power (derived quantities).

[SOURCE: ISO 80000-1:2009, 3.1, modified — Notes 1 to 6 to entry have been removed; EXAMPLEs 1 and 2 and new Note 1 to entry have been added.]

xtdMeasureWithUnit

[source ISO 12006-3 names ]

Table C.1 — BS EN ISO 23386:2020 Base quantities from ISO 80000-1:2009

Base quantitiesDescriptionDimensionSI unitSI symbol
LengthOne-dimensional extent of an objectLmetrem
MassA measure of resistance to accelerationMkilogramkg
TimeThe duration of an eventTseconds
Electric currentRate of flow of electrical charge per unit timeIampereA
Thermodynamic temperatureAverage kinetic energy per degree of freedom of a systemθkelvinK
Amount of substanceNumber of particles compared to the number of atoms in 0,012 kg of 12CNmolemol
Luminous intensityWavelength-weighted power of emitted light per unit solid angleJcandelacd
BS EN ISO 23386:2020 – Annex C

Table C.2 — BS EN ISO 23386:2020 Examples of derived quantities from ISO 80000-1:2009

Derived quantitiesDescriptionDimensionSI derived unitSI symbol
AccelerationChange of the speed or velocity per unit timeLT−2metre per sec- ond per secondm s−2
Plane angleRatio of circular arc length to radius1radianrad
Solid angleRatio of area on a sphere to its radius squared1steradiansr
CapacitanceStored charge per unit electric potentialL−2M−1T4I2faradF
Electric field
strength
Strength of the electric fieldLMT−3I−1volt per metreV m−1
Magnetic field
strength
Strength of a magnetic fieldL−1Iampere per metreA m−1
Electric chargeThe force per unit electric field strengthTIcoulombC
Electrical conduct- anceMeasure for how easily current flows through
a material
L−2M−1T3I2siemensS
Current densityElectric current per unit cross-section areaL−2Iampere per square metreA m−2
EnergyCapacity of a body or system to do workL2MT−2jouleJ
EntropyLogarithmic measure of the number of availa- ble states of a systemL2MT−2θ−1joule per kelvinJ K−1
ForceTransfer of momentum per unit timeLMT−2newtonN
FrequencyNumber of (periodic) occurrences per unit timeT−1hertzHz
ImpedanceResistance to an alternating current of a given frequency, including effect on phaseL2MT−3I−2ohmΩ
InductanceMagnetic flux generated per unit current
through a circuit
L2MT−2I−2henryH
Magnetic flux
density
Measure for the strength of the magnetic fieldMT−2I−1teslaT
Volume densityMass per unit volumeL−3Mkilogram per cubic metrekg m−3
PermittivityMeasure for how the polarization of a materi- al is affected by the application of an external electric fieldL−3M−1T4I2farad per metreF m−1
Electric potentialEnergy required to move a unit charge through an electric field from a reference pointL2MT−3I2voltV
PressureForce per unit areaL−1MT−2pascalPa
PowerRate of transfer of energy per unit timeL2MT−3wattW
Electrical resistanceElectric potential per unit electric currentL2MT−3I−2ohmΩ
Electrical resistivityBulk property equivalent of electrical resist- anceL3MT−3I−2ohm metreΩ m
AreaExtent of a surfaceL2square metrem2
Thermal conductiv- ityMeasure for the ease with a material con- ducts heatLMT3θ−1watt per metre per kelvinw m−1 k−1
VelocitySpeed and direction of an objectLT−1metre per secondm s−1
Angular speedThe angle incremented in a plane by a seg- ment connecting an object and a reference point per unit timeT−1radian per secondrad s−1
VolumeThree-dimensional extent of an objectL3cubic metrem3
BS EN ISO 23386:2020 – Annex C
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