Table 7.4 -- Units whose label begins with A-L

Label Symbol Quantity / Definition EQ label Code References
AMP_PER_METRE A/m lineic electric current, linear electric current density; Electric current in a conducting sheet divided by the width of the sheet.
magnetic field strength; Vector quantity, the rotation (curl) of which is equal to the sum of the electric current density and the time derivative of the electric flux density.		 LINEIC_ELECTRIC_CURRENT 1 ISO 31-5, 5-16.a;
ISO 31-5, 5-17.a; ISO 31-5, 5-28.a
AMP_PER_SQ_M_KELVIN_SQD A/(m2 · K2) thermionic emission current density THERMION_EMISSION_CUR_DENS 2 ISO 31-13, 13-27.a
AMP_PER_SQ_METRE A/m2 areic electric current, electric current density; Vector quantity, the integral of which over a given surface is equal to the electric current flowing through that surface. AREIC_ELECTRIC_CURRENT 3 ISO 31-5, 5-15.a
AMPERE A electric current (SI base unit); That constant electric current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per metre of length. ELECTRIC_CURRENT 4 ISO 31-0, Table 1;
ISO 31-5, 5-1.a;
ISO 31-5, 5-18.a
BECQUEREL Bq activity (of a radio nuclide); Average number of spontaneous nuclear transitions from a particular energy state occurring in an amount of a radio nuclide in a small time interval, divided by that interval.
1 Bq = 1 s-1		 RADIONUCLIDE_ACTIVITY 10 ISO 31-0, Table 3;
ISO 31-9, 9-33.a;
ISO 31-10, 10-49.a
BECQUEREL_PER_CUBIC_METRE Bq/m3 volumic activity, activity concentration; Activity (of a radio nuclide) divided by the total volume of the sample. VOLUMIC_ACTIVITY 11 ISO 31-9, 9-35.a
BECQUEREL_PER_KG Bq/kg massic activity, specific activity; Activity (of a radio nuclide) divided by the total mass of the sample. MASSIC_ACTIVITY 12 ISO 31-9, 9-34.a
BEL B field quantity ratio (level), power quantity ratio (level); Common logarithm of a power quantity ratio, or twice the common logarithm of a field quantity ratio.
1 B is the level of a power quantity when lg (P/P0) = 1 where P and P0 represent two powers, P0 being a reference power.
1 B is also the level of a field quantity when 2 lg (F/F0) = 1 where F and F0 represent two amplitudes of the same kind, F0 being a reference amplitude;
The bel is a non-coherent unit based on common logarithms (base 10) for logarithmic quantities and is often used instead of the Np. 1 B = (1/2) ln 10 Np = 1,151 293 Np (approximately)		 FIELD_OR_POWER_LEVEL 13 ISO 31-2, 2-9.b;
ISO 31-2, 2-10.b;
ISO 31-7, 7-21.a;
ISO 31-7, 7-22.a;
ISO 31-7, 7-28.a
CANDELA cd luminous intensity (SI base unit); The luminous intensity, in a given direction, of a source that emits monochromatic radiation of a frequency 540 x 1012 Hertz, and that has a radiant intensity in that direction of 1 / 683 watt per steradian. LUMINANCE_INTENSITY 14 ISO 31-0, Table 1;
ISO 31-6, 6-29.a
CD_PER_SQ_METRE cd/m2 luminance; At a point on a surface and in a given direction, the luminous intensity of an element of the surface, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction. LUMINANCE 15 ISO 31-6, 6-32.a
COULOMB C electric charge; Integral of electric current over time.
1 C = 1 s · A		 ELECTRIC_CHARGE 16 ISO 31-0, Table 2;
ISO 31-5, 5-2.a;
ISO 31-5, 5-8.a;
ISO 31-8, 8-43.a;
ISO 31-9, 9-6.a
COULOMB_METRE C · m electric dipole moment; Vector quantity, the vector product of which with the electric field strength of a homogenous field is equal to the torque.
1 C · m = 1 m · s · A		 ELECTRIC_DIPOLE_MOMENT 17 ISO 31-5, 5-14.a;
ISO 31-8, 8-32.a
COULOMB_METRE_SQD_PER_VOLT C · m2/V electric polarizability of molecule; Induced electric dipole moment divided by electric field strength.
1 C · m2/V = 1 (s4 · A2)/kg		 ELECTRIC_POLARIZABILITY 18 ISO 31-8, 8-33.a
COULOMB_PER_CUBIC_M C/m3 volume density of charge, electric charge density; Charge divided by volume.
1 C/m3 = 1 (s · A)/m3		 VOLUME_DENSITY_CHARGE 19 ISO 31-5, 5-3.a
COULOMB_PER_KG C/kg exposure (ionizing radiation); The total electric charge of the ions of the same sign produced when all the electrons (negative and positive) liberated by photons in an element of air are stopped in air, divided by the mass of that element.
1 C/kg = 1 (s · A)/kg		 EXPOSURE 20 ISO 31-10, 10-58.a
COULOMB_PER_KG_SEC C/(kg · s) exposure rate (ionizing radiation); Exposure (ionizing radiation) divided by time.
1 C/(kg · s) = 1 A/kg		 EXPOSURE_RATE 21 ISO 31-10, 10-59.a
COULOMB_PER_MOLE C/mol molar charge; Charge carried per amount of substance.
The Faraday constant is the charge carried per mole of electrons.
1 C/mol = 1 (s · A)/mol		 MOLAR_CHARGE 22 ISO 31-8, 8-45.a
COULOMB_PER_SQ_M C/m2 surface density of charge, electric flux density; Charge divided by surface area.
1 C/m2 = 1 (s · A)/m2		 SURFACE_DENSITY_CHARGE 23 ISO 31-5, 5-4.a;
ISO 31-5, 5-7.a;
ISO 31-5, 5-13.a
CUBIC_M_PER_CUBIC_M m3/m3 volume fraction; dimensionless
1 m3/m3 = 1		 VOLUME_FRACTION 24 ISO 31-8, 8-15.a;
ISO 31-0, 2.3.3
CUBIC_METRE m3 volume VOLUME 25 ISO 31-1, 1-6.a;
ISO 31-3, 3-21.a
CUBIC_METRE_PER_COULOMB m3/C reciprocal volumic charge, reciprocal charge density; Volume divided by charge.
Used to express the relationship between electric field strength, magnetic field, and current density, in an isotropic conductor, known as the Hall coefficient.		 RECIPROCAL_VOLUMIC_CHARGE 26 ISO 31-13, 13-20.a
CUBIC_METRE_PER_KG m3/kg specific volume; Volume divided by mass. SPECIFIC_VOLUME 27 ISO 31-3, 3-4.a
CUBIC_METRE_PER_MOLE m3/mol molar volume; Volume divided by amount of substance. MOLAR_VOLUME 28 ISO 31-8, 8-6.a
CUBIC_METRE_PER_SEC m3/s volume flow rate; Volume of matter which crosses a given surface divided by time. VOLUME_FLOW_RATE 29 ISO 31-3, 3-30.a;
ISO 31-7, 7-13.a;
ISO 31-10, 10-28.a
DAY d time; 1 d = 24 h = 86 400 s (exactly) TIME 31 ISO 31-0, Table 4;
ISO 31-1, 1-7.d
DB dB field quantity ratio (level), power quantity ratio (level); 1 dB = 10-1 B (exactly) = 1,151 293 x 10-1Np (approximately) FIELD_OR_POWER_LEVEL 32 ISO 31-2, 2-9.a (remarks);
ISO 31-2, 2-10.a (remarks);
ISO 1000, Annex A 7-21
DB_PER_METRE dB/m power ratio (level) gradient; Rate of power ratio change as a function of distance. POWER_LEVEL_LENGTH_GRADIENT 33 ISO 31-0, 2.3.2.2 (derived)
DB_PER_METRE_KHZ dB/(m · kHz) power ratio (level) distance and frequency gradient; Rate of power ratio change as a function of distance and spectral frequency. POWER_LEVEL_LENGTH_FREQ 34 ISO 31-0, 2.3.2.2 (derived)
DB_PER_METRE_KHZ_PER_METRE dB/(m · kHz)/m gradient of power ratio (level) distance and frequency gradient; Rate of change of power ratio change as a function of distance and spectral frequency. GRAD_POWER_LEVEL_LEN_FREQ 35 ISO 31-0, 2.3.2.2 (derived)
DB_PER_OCTAVE none power ratio (level) frequency gradient; Rate of power ratio change as a function of spectral frequency octave. POWER_LEVEL_FREQ_GRADIENT 36 ISO 31-0, 2.3.2.2 (derived)
DB_PER_SQ_METRE dB/m2 areic power ratio (level); Power level divided by area. AREIC_POWER_LEVEL 37 ISO 31-0, 2.3.2.2 (derived)
DB_REF_ONE_MICROPASCAL dB (re 1 μPa) pressure power quantity ratio (level); 1 dB (re 1 μPa) is the level of a pressure power quantity when lg (P/P0) = 0,1 where P and P0 represent two pressure powers, P0 being a reference power of 1 μPa. PRESSURE_POWER_LEVEL 38 ISO 31-0, 2.3.2.2 (derived)
DEGREE_ARC º plane angle; The angle between two half-lines terminating at the same point is defined as the ratio of the length of the included arc of the circle (with its centre at that point) to the radius of that circle.
1º = (π / 180) rad (exactly)		 PLANE_ANGLE 39 ISO 31-0, Table 4;
ISO 31-1, 1-1.b;
ISO 31-13, 13-4.b
DEGREE_C ºC thermodynamic temperature; A special name for the kelvin for use in stating values of Celsius temperature.
t = T - T0 where T0 = 273,15 K (exactly)		 THERMO_TEMPERATURE 40 ISO 31-0, Table 2;
ISO 31-4, 4-2.a
DEGREE_C_HOUR ºC · h integrated thermodynamic temperature; Thermodynamic temperature integrated over an interval of time.
1 ºC · h = 3,6 x 103 K · s (exactly)		 INTEGRATED_THERMO_TEMP 41 ISO 31-0, 2.3.2.2 and 2.3.4 (derived)
DEGREE_C_PER_HOUR ºC/h thermodynamic temperature change rate; Thermodynamic temperature change over an interval of time, divided by that time.
1 ºC/h = 1 / 3,6 x 10-3 K/s (exactly)		 THERMO_TEMP_CHANGE_RATE 42 ISO 31-0, 2.3.2.2 and 2.3.4 (derived)
DEGREE_C_PER_METRE ºC/m lineic thermodynamic temperature gradient; Thermodynamic temperature change over a distance, divided by that distance.
1 ºC/m = 1 K/m (exactly)		 LINEIC_THERMO_TEMP_GRADIENT 43 ISO 31-0, 2.3.2.2 (derived)
DEGREE_C_PER_SEC ºC/s thermodynamic temperature change rate; Thermodynamic temperature change over an interval of time, divided by that time.
1 ºC/s = 1 K/s (exactly)		 THERMO_TEMP_CHANGE_RATE 44 ISO 31-0, 2.3.2.2 (derived)
ELECTRONVOLT eV energy; The kinetic energy acquired by an electron in passing through a potential difference of 1 volt in a vacuum. Its value is experimentally determined as 1,602 177 x 10-19 J (approximately) ENERGY 45 ISO 31-0, Table 6;
ISO 31-9, 9-32.b;
ISO 31-9, 9-38.b;
ISO 31-9, 9-39.b;
ISO 31-9, 9-40.b;
ISO 31-10, 10-1.b;
ISO 31-10, 10-2.b;
ISO 31-10, 10-25.b;
ISO 31-13, 13-25.b;
ISO 31-13, 13-26.b;
ISO 31-13, 13-28.b;
ISO 31-13, 13-35.b;
ISO 31-13, 13-38.b
ELECTRONVOLT_M_SQD eV · m2 total atomic stopping power; Total linear stopping power divided by the number density of the atoms in the substance.
1 eV · m2 = (1,602 177 33 ± 0,000 000 49) x 10-19 J · m2 (approximately)		 TOTAL_ATOMIC_STOPPING_POWER 46 ISO 31-10, 10-19.b
ELECTRONVOLT_M_SQD_PER_KG (eV · m2)/kg total mass stopping power; Total linear stopping power divided by the volumic mass of the substance.
1 (eV · m2)/kg = (1,602 177 33 ± 0,000 000 49) x 10-19 (J · m2)/kg (approximately)		 TOTAL_MASS_STOPPING_POWER 47 ISO 31-10, 10-20.b
ELECTRONVOLT_PER_METRE eV/m total linear stopping power, linear energy transfer; For an ionizing charged particle, the energy imparted locally to matter in traversing a small distance through the matter, divided by that distance. TOTAL_LINEAR_STOPPING_POWER 48 ISO 31-10, 10-18.b;
ISO 31-10, 10-54.b
FARAD F capacitance; Charge divided by potential difference.
1 F = 1 C/V = 1 (s4 · A2)/(m2 · kg)		 CAPACITANCE 49 ISO 31-0, Table 2;
ISO 31-5, 5-9.a
FARAD_PER_METRE F/m permittivity, electric constant, dielectric constant; A measure of the ability of a material to resist the formation of an electric field within it.
1 F/m = 1 (s4 · A2)/(m3 · kg)		 PERMITTIVITY 50 ISO 31-5, 5-10.a
GEOPOTENTIAL_METRE gpm geopotential energy length (height), geopotential specific energy; Height proportional to the potential energy of mass (geopotential) at this height relative to the geoid.
The geopotential metre varies with geodetic latitude. On Earth at mid-latitudes it equals 0,98 m (approximately).		 GEOPOTENTIAL_ENERGY_LENGTH 53 none
GRAM g mass; For historical reasons the name of the base unit for mass, the kg, contains the name of the SI prefix "kilo". A gram is a special name given to unit kg x 10-3 that is used instead of "millikilogram". MASS 55 ISO 31-0, 3.2.4
GRAM_PER_CUBIC_CM g/cm3 volumic mass, mass density, density; Mass divided by volume.
1 g/cm3 = 103 kg/m3 (exactly)		 VOLUMIC_MASS 56 ISO 31-3, 3-2.b;
ISO 31-7, 7-8.a;
ISO 31-8, 8-11.a;
ISO 31-0, 2.3.2.3
GRAM_PER_CUBIC_M g/m3 volumic mass, mass density, density; Mass divided by volume.
1 g/m3 = 10-3 kg/m3 (exactly)		 VOLUMIC_MASS 57 ISO 31-3, 3-2.b;
ISO 31-7, 7-8.a;
ISO 31-8, 8-11.a;
ISO 31-0, 2.3.2.3
GRAM_PER_GRAM g/g mass fraction; dimensionless
1 g/g = 1 kg/kg = 1		 MASS_FRACTION 58 ISO 31-8, 8-12.a;
ISO 31-0, 2.3.3;
ISO 31-0, 2.3.2.3
GRAM_PER_KILOGRAM g/kg mass fraction; dimensionless
1 g/kg = 10-3 kg/kg = 10-3 (exactly)		 MASS_FRACTION 59 ISO 31-8, 8-12.a;
ISO 31-0, 2.3.3;
ISO 31-0, 2.3.2.3
GRAY Gy absorbed dose (ionizing radiation); For any ionizing radiation, the energy imparted to an element of irradiated matter divided by the mass of this element.
For indirectly ionizing (uncharged) particles, the sum of the initial kinetic energies of all charged particles liberated in an element of matter, divided by the mass of that element.
1 Gy = 1 J/kg = 1 m2/s2		 ABSORBED_DOSE 60 ISO 31-0, Table 3;
ISO 31-10, 10-51.a;
ISO 31-10, 10-55.a
GRAY_PER_SECOND Gy/s absorbed dose rate (ionizing radiation), kerma rate; The absorbed dose (ionizing radiation) over an interval of time, divided by that time.
1 Gy/s = 1 W/kg = 1 m2/s3		 ABSORBED_DOSE_RATE 61 ISO 31-10, 10-53.a;
ISO 31-10, 10-56.a
HENRY H inductance (magnetic); For a thin conducting loop, the magnetic flux through the loop, caused by an electric current in the loop, divided by that current.
For two thin conducting loops (m and n), the magnetic flux through one loop, due to an electric current in the other loop, divided by that current.
1 H = 1 Wb/A = 1 (m2 · kg)/(s2 · A2)		 INDUCTANCE 63 ISO 31-0, Table 2;
ISO 31-5, 5-22.a;
ISO 31-5, 5-39.a
HENRY_PER_METRE H/m permeability (magnetic); The ability of a substance to acquire magnetization when placed in a magnetic field.
1 H/m = 1 (m · kg)/(s2 · A2)		 MAGNETIC_PERMEABILITY 64 ISO 31-5, 5-24.a
HERTZ Hz frequency; Number of cycles or revolutions divided by time. 1 Hz = 1 s-1
1 Hz is the frequency of a periodic phenomenon of which the period is 1 second.		 FREQUENCY 65 ISO 31-0, Table 2;
ISO 31-2, 2-3.a;
ISO 31-5, 5-41.a;
ISO 31-6, 6-1.a;
ISO 31-7, 7-2.a
HOUR h time; 1 h = 60 min = 3 600 s (exactly) TIME 66 ISO 31-0, Table 4;
ISO 31-1, 1-7.c
INT_SOLAR_FLUX_UNIT none international solar flux unit; Unit of radio emission from the Sun, measured at 10.7 cm (approximately 2 800 MHz).
1 SFU = 104 Jy = 10-22 W/(m2 · Hz) (exactly)		 FLUX_DENSITY 67 ISO 31-0, 2.3.1 and 2.3.2 (derived)
INV_CUBIC_CM 1/cm3 volumetric entity density (any elementary entity: atoms, molecules, ions, electrons, other particles, or specified groups of such particles); Number of molecules or particles divided by volume.
1/cm3 = 10-6 1/m3		 VOLUMETRIC_ENTITY_DENSITY 68 ISO 31-10, 10-27.a;
ISO 31-0, 2.3.2.3
INV_CUBIC_CM_SEC 1/(cm3 · s) volumetric entity emittance or capture rate (any elementary entity: atoms, molecules, ions, electrons, other particles, or specified groups of such particles); Number of molecules or particles divided by volume, per time. 1/(cm3 · s) = 10-6 1/(m3 · s) VOLUMETRIC_ENTITY_EMIT_RATE 69 ISO 31-10, 10-35.a;
ISO 31-0, 2.3.2.3
INV_CUBIC_METRE 1/m3 volumetric entity density (any elementary entity: atoms, molecules, ions, electrons, other particles, or specified groups of such particles); Number of molecules or particles divided by volume. VOLUMETRIC_ENTITY_DENSITY 70 ISO 31-8, 8-10.a;
ISO 31-10, 10-27.a;
ISO 31-10, 10-29.a;
ISO 31-13, 13-30.a
INV_CUBIC_METRE_EV 1/(m3 · eV) density of states; 1/(m3 · eV) = (6,241 5061 4 ± 0,0001 0011 9) x 1018 1/(m3 · J) (approximately) DENSITY_STATES 71 ISO 31-13, 13-17.b
INV_CUBIC_METRE_JOULE 1/(m3 · J) density of states DENSITY_STATES 72 ISO 31-13, 13-17.a
INV_CUBIC_METRE_SEC 1/(m3 · s) volumetric entity emittance or capture rate (any elementary entity: atoms, molecules, ions, electrons, other particles, or specified groups of such particles); Number of molecules or particles divided by volume, per time. VOLUMETRIC_ENTITY_EMIT_RATE 73 ISO 31-10, 10-34.a;
ISO 31-10, 10-35.a
INV_HENRY 1/H reluctance; Magnetic potential difference divided by magnetic flux.
1/H = 1 A/Wb = 1 (s2 · A2)/(m2 · kg)		 RELUCTANCE 74 ISO 31-5, 5-38.a
INV_KELVIN 1/K linear expansion coefficient; Coefficient of linear expansion divided by thermodynamic temperature change.
cubic expansion coefficient; Coefficient of volumic expansion divided by thermodynamic temperature change.
relative pressure coefficient; Coefficient of pressure change divided by thermodynamic temperature change.		 LINEAR_EXPANSION_COEFF 75 ISO 31-4, 4-3.a
INV_METRE 1/m linear attenuation coefficient, linear extinction coefficient, linear propagation coefficient, linear phase coefficient; The ratio of a quantity which is a function of distance divided by the distance between the measurements.
repetency, wave number, angular repetency, angular wave number; The reciprocal of the wavelength or the number of waves per unit length (or angle) along the direction of propagation.
curvature, vergence		 LINEAR_ATTENUATION_COEFF 76 ISO 31-1, 1-4.a;
ISO 31-2, 2-6.a;
ISO 31-2, 2-7.b;
ISO 31-2, 2-13.a;
ISO 31-6, 6-4.a;
ISO 31-6, 6-5.b;
ISO 31-6, 6-42.a;
ISO 31-6, 6-46.a;
ISO 31-7, 7-6.a;
ISO 31-7, 7-7.b;
ISO 31-7, 7-26.a;
ISO 31-9, 9-9.a;
ISO 31-10, 10-7.a;
ISO 31-10, 10-13.a;
ISO 31-10, 10-23.a;
ISO 31-13, 13-2.a;
ISO 31-13, 13-10.b
INV_MOLE 1/mol molar density (Avogadro constant); Number of molecules divided by amount of substance. MOLAR_DENSITY 77 ISO 31-8, 8-4.a
INV_PASCAL 1/Pa compressibility; 1/Pa = 1 (m · s2)/kg COMPRESSIBILITY 78 ISO 31-3, 3-19.a;
ISO 31-4, 4-5.a
INV_RADIAN 1/rad reciprocal plane angle RECIPROCAL_PLANE_ANGLE 79 ISO 31-0, 2.3.2.2 (derived)
INV_SEC_STERADIAN 1/(s · sr) photon intensity; In a given direction from a source, the photon flux leaving the source, or an element of the source, in an element of solid angle containing the given direction, divided by that element of solid angle. PHOTON_INTENSITY 80 ISO 31-6, 6-24.a
INV_SECOND 1/s rate; Number of occurrences divided by time.
angular frequency; Number of cycles or revolutions divided by time.		 RATE 81 ISO 31-2, 2-3.b;
ISO 31-2, 2-4.b;
ISO 31-2, 2-11.a;
ISO 31-5, 5-41.b;
ISO 31-5, 5-42.b;
ISO 31-6, 6-2.b;
ISO 31-6, 6-23.a;
ISO 31-7, 7-4.b;
ISO 31-7, 7-23.a;
ISO 31-9, 9-14.b;
ISO 31-9, 9-15.b;
ISO 31-9, 9-36.a;
ISO 31-13, 13-11.b
INV_SQ_CM_SEC_SR_EV 1/(cm2 · s · sr · eV) particle flux density; At a point on a surface and in a given direction, the charged particle flux of an element of the surface as a function of particle energy, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction.
1/(cm2 · s · sr · eV) = 10-6 1/(m2 · s · sr · eV) (exactly)
Used in radio astronomy to measure the charged particle energy incident on the receiving body within a specified energy range.		 PARTICLE_FLUX_DENSITY 82 ISO 31-0, 2.3.2.3 (derived)
INV_SQ_CM_SEC_STERADIAN 1/(cm2 · s · sr) photon luminance, photon radiance; At a point on a surface and in a given direction, the photon intensity of an element of the surface, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction.
1/(cm2 · s · sr) = 10-4 1/(m2 · s · sr) (exactly)		 PHOTON_LUMINANCE 83 ISO 31-6, 6-25.a;
ISO 31-0, 2.3.2.3
INV_SQ_M_SEC_SR_EV 1/(m2 · s · sr · eV) particle flux density; At a point on a surface and in a given direction, the charged particle flux of an element of the surface as a function of particle energy, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction.
Used in radio astronomy to measure the charged particle energy incident on the receiving body within a specified energy range.		 PARTICLE_FLUX_DENSITY 84 ISO 31-0, 2.3.2.2 (derived)
INV_SQ_M_SEC_STERADIAN 1/(m2 · s · sr) photon luminance, photon radiance; At a point on a surface and in a given direction, the photon intensity of an element of the surface, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction. PHOTON_LUMINANCE 85 ISO 31-6, 6-25.a
INV_SQ_METRE 1/m2 areal entity density (any elementary entity: atoms, molecules, ions, electrons, other particles, or specified groups of such particles); At a given point in space, the number of particles incident on a small sphere, divided by the cross-sectional area of that sphere. AREAL_ENTITY_DENSITY 86 ISO 31-6, 6-28.a;
ISO 31-10, 10-8.a
INV_SQ_METRE_SEC 1/(m2 · s) particle current density, particle flux density; At a given point in space, the number of particles incident on a small sphere in a small time interval, divided by the cross-sectional area of that sphere and by the time interval.
photon exitance, photon irradiance; At a point on a surface, the photon flux leaving, or incident on, an element of the surface, divided by the area of that element and by the time interval.		 PARTICLE_CURRENT_DENSITY 87 ISO 31-6, 6-26.a;
ISO 31-6, 6-27.a;
ISO 31-10, 10-9.a;
ISO 31-10, 10-12.a;
ISO 31-10, 10-31.a
INV_STERADIAN 1/sr reciprocal solid angle RECIPROCAL_SOLID_ANGLE 88 ISO 31-0, 2.3.2.2 (derived)
JANSKY Jy flux density; The jansky is a special unit for the strength (or flux density) of radio sources.
1 Jy = 10-26 W/(m2 · Hz) (exactly)		 FLUX_DENSITY 89 ISO 31-0, 2.3.1
JOULE J thermodynamic energy, work, quantity of heat; All kinds of energy.
1 J = 1 N·m = 1 (m2 · kg)/s2		 ENERGY 90 ISO 31-0, Table 2;
ISO 31-3, 3-26.a;
ISO 31-4, 4-6.a;
ISO 31-4, 4-20.a;
ISO 31-5, 5-52.a;
ISO 31-6, 6-7.a;
ISO 31-9, 9-10.a;
ISO 31-9, 9-32.a;
ISO 31-9, 9-38.a;
ISO 31-9, 9-39.a;
ISO 31-9, 9-40.a;
ISO 31-10, 10-1.a;
ISO 31-10, 10-2.a;
ISO 31-10, 10-25.a;
ISO 31-10, 10-50.a;
ISO 31-13, 13-25.a;
ISO 31-13, 13-26.a;
ISO 31-13, 13-28.a;
ISO 31-13, 13-35.a;
ISO 31-13, 13-38.a;
ISO 31-9, 9-39.a
JOULE_METRE_SQD J · m2 total atomic stopping power; 1 J · m2 = 1 (m4 · kg)/s2 TOTAL_ATOMIC_STOPPING_POWER 91 ISO 31-10, 10-19.a
JOULE_METRE_SQD_PER_KG (J · m2)/kg total mass stopping power; Total linear stopping power divided by the volumic mass of the substance.
1 (J · m2)/kg = 1 m4/s2		 TOTAL_MASS_STOPPING_POWER 92 ISO 31-10, 10-20.a
JOULE_PER_CUBIC_M J/m3 energy density; Energy in an element of volume, divided by that element.
1 J/m3 = 1 kg/(m · s2)		 ENERGY_DENSITY 93 ISO 31-5, 5-30.a;
ISO 31-6, 6-8.a;
ISO 31-7, 7-15.a
JOULE_PER_GRAM_K J/(g · K) specific heat capacity; Heat capacity (or entropy) divided by mass.
1 J/(g · K) = 103 J/(kg · K) (exactly)		 SPECIFIC_HEAT_CAPACITY 94 ISO 31-4, 4-16.a;
ISO 31-4, 4-19.a;
ISO 31-0, 2.3.2.3
JOULE_PER_KELVIN J/K heat capacity (or entropy); When the temperature of a system is increased by dT as a result of the addition of a small quantity of heat dQ, the quantity dQ/dT is the heat capacity.
1 J/K = 1 (m2 · kg)/(s2 · K)		 HEAT_CAPACITY 95 ISO 31-4, 4-15.a;
ISO 31-4, 4-18.a;
ISO 31-4, 4-22.a;
ISO 31-4, 4-23.a;
ISO 31-8, 8-37.a
JOULE_PER_KELVIN_MOLE J/(K · mol) molar entropy, molar heat capacity; Heat capacity (or entropy) divided by amount of substance.
1 J/(K · mol) = 1 (m2 · kg)/(s2 · K · mol)		 MOLAR_ENTROPY 96 ISO 31-8, 8-8.a;
ISO 31-8, 8-9.a;
ISO 31-8, 8-36.a
JOULE_PER_KG J/kg specific energy; Energy divided by mass.
1 J/kg = 1 m2/s2		 SPECIFIC_ENERGY 97 ISO 31-4, 4-21.a
JOULE_PER_KG_KELVIN J/(kg · K) specific heat capacity; Heat capacity (or entropy) divided by mass.
1 J/(kg · K) = 1 m2/(s2 · K)		 SPECIFIC_HEAT_CAPACITY 98 ISO 31-4, 4-16.a;
ISO 31-4, 4-19.a
JOULE_PER_KM J/km linear energy transfer; For an ionizing charged particle, the energy imparted locally to matter in traversing a small distance through the matter, divided by that distance.
1 J/km = 10-3 J/m (exactly)		 LINEAR_ENERGY_TRANSFER 99 ISO 31-10, 10-18.a, ISO 31-10, 10-54.a;
ISO 31-0, 2.3.2.3
JOULE_PER_M_FOURTH_PWR J/m4 spectral concentration of radiant energy density (in terms of wavelength), spectral radiant energy density (in terms of wavelength); Radiant energy density in an infinitesimal wavelength interval, divided by the range of that interval.
1 J/m4 = 1 kg/(m2 · s2)		 SPECTRAL_RAD_ENERGY_DENSITY 100 ISO 31-6, 6-9.a
JOULE_PER_METRE J/m linear energy transfer; For an ionizing charged particle, the energy imparted locally to matter in traversing a small distance through the matter, divided by that distance.
1 J/m = 1 (m · kg)/s2		 LINEAR_ENERGY_TRANSFER 101 ISO 31-10, 10-18.a, ISO 31-10, 10-54.a
JOULE_PER_MOLE J/mol molar energy; Thermodynamic energy divided by amount of substance.
1 J/mol = 1 (m2 · kg)/(s2 · mol)		 MOLAR_ENERGY 102 ISO 31-8, 8-7.a;
ISO 31-8, 8-17.a;
ISO 31-8, 8-28.a
JOULE_PER_SQ_METRE J/m2 radiant energy fluence, energy fluence, radiance exposure; At a given point in space, the radiant flux incident on a small sphere, divided by the cross-sectional area of that sphere.
1 J/m2 = 1 kg/s2		 RADIANT_ENERGY_FLUENCE 103 ISO 31-6, 6-11.a;
ISO 31-6, 6-17.a;
ISO 31-10, 10-10.a
JOULE_SECOND J · s Planck constant; Elementary quantum of action.
1 J · s = 1 (m2 · kg)/s		 PLANCK_CONSTANT 104 ISO 31-9, 9-7.a
KELVIN K thermodynamic temperature (SI base unit); The fraction 1 / 273,16 of the thermodynamic temperature of the triple point of water. THERMO_TEMPERATURE 105 ISO 31-0, Table 1;
ISO 31-4, 4-1.a;
ISO 31-13, 13-12.a;
ISO 31-13, 13-29.a;
ISO 31-13, 13-36.a
KELVIN_PER_KM K/km lineic thermodynamic temperature gradient; Thermodynamic temperature difference divided by distance.
1 K/km = 10-3 K/m (exactly)		 LINEIC_THERMO_TEMP_GRADIENT 106 ISO 31-0, 2.3.2.2 (derived);
ISO 31-0, 2.3.2.3
KELVIN_PER_METRE K/m lineic thermodynamic temperature gradient; Thermodynamic temperature difference divided by distance. LINEIC_THERMO_TEMP_GRADIENT 107 ISO 31-0, 2.3.2.2 (derived)
KELVIN_PER_SEC K/s thermodynamic temperature change rate; Thermodynamic temperature change over an interval of time, divided by that time. THERMO_TEMP_CHANGE_RATE 108 ISO 31-0, 2.3.2.2 and 2.3.4 (derived)
KELVIN_PER_WATT K/W thermal resistance; Temperature difference divided by heat flow rate.
1 K/W = 1 (m2 · kg · K)/s3		 THERMAL_RESISTANCE 109 ISO 31-4, 4-12.a
KELVIN_SECOND K · s integrated thermodynamic temperature; Thermodynamic temperature integrated over an interval of time. INTEGRATED_THERMO_TEMP 110 ISO 31-0, 2.3.2.2 and 2.3.4 (derived)
KG_METRE_PER_SEC kg · m/s momentum; Product of mass and velocity. MOMENTUM 111 ISO 31-3, 3-8.a
KG_METRE_SQD kg · m2 moment of inertia; The moment of inertia of a body about an axis is the sum (integral) of the products of its elements of mass and the squares of their distances from the axis. MOMENT_INERTIA 112 ISO 31-3, 3-7.a
KG_METRE_SQD_PER_SEC (kg · m2)/s moment of momentum, angular momentum; The moment of momentum of a particle about a point is equal to the vector product of the radius vector from this point to the particle and the momentum of the particle. ANGULAR_MOMENTUM 113 ISO 31-3, 3-11.a
KG_PER_CUBIC_METRE kg/m3 volumic mass, mass density, density; Mass divided by volume. VOLUMIC_MASS 114 ISO 31-3, 3-2.a;
ISO 31-7, 7-8.a;
ISO 31-8, 8-11.a
KG_PER_KG kg/kg mass fraction; dimensionless
1 kg/kg = 1		 MASS_FRACTION 115 ISO 31-8, 8-12.a;
ISO 31-0, 2.3.3
KG_PER_LITRE kg/l volumic mass, mass density, density; Mass divided by volume.
1 kg/l = 10-3 kg/m3 (exactly)		 VOLUMIC_MASS 116 ISO 31-3, 3-2.c;
ISO 31-8, 8-11.b
KG_PER_METRE kg/m lineic mass, linear density; Mass divided by length LINEIC_MASS 117 ISO 31-3, 3-5.a
KG_PER_MOLE kg/mol molar mass; Mass divided by amount of substance. MOLAR_MASS 118 ISO 31-8, 8-5.a
KG_PER_SECOND kg/s mass flow rate; Mass of matter which crosses a given surface divided by time. MASS_FLOW_RATE 119 ISO 31-3, 3-29.a
KG_PER_SQ_METRE kg/m2 surface density; Mass divided by area. SURFACE_DENSITY 120 ISO 31-3, 3-6.a;
ISO 31-10, 10-22.a
KILOGRAM kg mass (SI base unit); Equal to the mass of the international prototype of the kilogram. MASS 121 ISO 31-0, Table 1;
ISO 31-3, 3-1.a;
ISO 31-8, 8-31.a;
ISO 31-9, 9-4.a;
ISO 31-9, 9-5.a;
ISO 31-9, 9-28.a;
ISO 31-13, 13-31.a
KM_PER_HOUR km/h velocity; Distance divided by time.
1 km/h = 1 / 3,6 m/s (exactly)		 VELOCITY 123 ISO 31-1, 1-10.b
LITRE l, L volume; The two symbols for the litre are on an equal footing.
1 l = 1 dm3 = 10-3 m3
Prior to 1964, the litre was equal to 1,000 028 dm3.		 VOLUME 126 ISO 31-0, Table 4;
ISO 31-1, 1-6.b
LITRE_PER_HOUR L/h volume flow rate; 1 L/h = 1 / 3,6 x 10-6 m3/s (exactly) VOLUME_FLOW_RATE 127 ISO 31-0, 2.3.2.2 (derived)
LITRE_PER_SECOND L/s volume flow rate; 1 L/s = 10-3 m3/s (exactly) VOLUME_FLOW_RATE 128 ISO 31-0, 2.3.2.2 (derived)
LUMEN lm luminous flux; 1 lm = 1 cd · sr LUMINANCE_FLUX 130 ISO 31-0, Table 2;
ISO 31-6, 6-30.a
LUMEN_HOUR lm · h quantity of light; Time integral of luminous flux.
1 lm · h = 3 600 lm · s (exactly)		 QUANTITY_LIGHT 131 ISO 31-6, 6-31.b
LUMEN_PER_SQ_METRE lm/m2 luminous exitance; At a point on a surface, the luminous flux leaving an element of the surface, divided by the area of that element. LUMINANCE_EXITANCE 132 ISO 31-6, 6-33.a
LUMEN_PER_WATT lm/W luminous efficacy, spectral luminous efficacy, luminous efficacy at a specified wavelength; Luminous flux divided by power (radiant flux).
1 lm/W = 1 (s3 · lm)/(m2 · kg)		 LUMINANCE_EFFICIENCY 133 ISO 31-6, 6-36.a
LUMEN_SECOND lm · s quantity of light; Time integral of luminous flux. QUANTITY_LIGHT 134 ISO 31-6, 6-31.a
LUX lx illuminance; At a point on a surface, the luminous flux incident on an element of the surface, divided by the area of that element.
1 lx = 1 lm/m2		 ILLUMINANCE 135 ISO 31-0, Table 2;
ISO 31-6, 6-34.a
LUX_HOUR lx · h light exposure; Time integral of illuminance.
1 lx · h = 3 600 lx · s (exactly)		 LIGHT_EXPOSURE 136 ISO 31-6, 6-35.b
LUX_SECOND lx · s light exposure; Time integral of illuminance. LIGHT_EXPOSURE 137 ISO 31-6, 6-35.a