Quantity | Dimension | Alternatives | Root definition and Notes |
Basic SI quantities |
Length | m | m | meter |
Mass | kg | kg | kilogram |
Time | s | s | second |
Current, electric | A | A | ampere |
Temperature | K | K | kelvin |
Quantity of substance | mol | mol | mole |
Luminosity | Luminous intensity | cd | cd | candle |
Pseudo-dimensional quantities: |
Plane angle | 1 | rad | radian |
Solid angle | 1 | sr | steradian |
Universal dimensionless quantities |
Count of events | Number of instances | 1 | | This covers all kinds of enumerations |
Probability of an event | 1 | | Real number in a dimensionless interval [0,1] |
Ratio of commensurable quantities | 1 | | Q1/Q2, with Q1 and Q2 having the same dimension |
Relative variation | 1 | | ΔQ/Q, for any quantity Q |
Logarithmic ratio logb(A/A') in any base b | 1 | | Applicable to any ratio of commensurable quantities |
Logarithmic scale differential | Relative differential | 1 | | d{ln(Q)} = dQ/Q, for any quantity Q |
Pseudo-dimensional quantities: |
Phase | Phase angle | 1 | rad | φ typically in exp(i(ωt+φ)) |
Logarithmic ratio Log(P/P')/10 | 1 | dB | decibel. Uses base-10 logarithm. Applies to power P |
Logarithmic ratio Log(X/X')/20 | 1 | dB | decibel. Uses base-10 logarithm. Applies to amplitudes X |
Gain or Loss of a device | 1 | usually in dB | [Output]/[Input], provided they are commensurable quantities |
Attenuation | Amplification (generic) | 1 | usually in dB | [Quantity(p)]/[Quantity(p')], with p being some parameter |
Logarithmic ratio ln(A/A') | 1 | Np | Neper. Uses natural logarithm |
Logarithmic scale probability density | 1 | 1/Np | [Probability]/[Natural-logarithmic ratio] |
Operators |
Derivative with respect to time | s-1 | | d/dt, ∂/∂t |
Derivative with respect to a length | m-1 | | d/dr, ∂/∂r, r = x | y | z |
Nabla ( ∇ ) | div | grad | rot | curl | m-1 | | Any derivative-like construct with respect to a distance |
Laplace operator | Laplacian | m-2 | | ∇2 = ∂2/∂x2 + ∂2/∂y2 + ∂2/∂z2 |
D'Alembert operator | D'Alembertian | m-2 | | (1/c2)∂2/∂t2 - ∂2/∂x2 - ∂2/∂y2 - ∂2/∂z2 |
Multiple derivatives with respect to time | s-p | | dp/dtp, ∂p/∂tp; for p = 1,2,3,.. |
Multiple derivatives with respect to a length | m-p | | dp/drp, ∂p/∂rp; for p = 1,2,3,..., r = x | y | z |
Quantities related only to time |
Time | Duration | s | s | second |
Half life | s | | of a non-conservative / decaying quantity |
Settling time | s | typically dB/s | Used to describe transient phenomena |
Relaxation time | s | | Used for returns to equilibria |
Activity | Frequency of events | s-1 | | [Counts]/[Time] |
Count rate | Expectation frequency | s-1 | | [Counts]/[Time] |
Relative growth rate | s-1 | | [Relative variation]/[Time] |
Relative evolution rate | Log-scale evolution rate | s-1 | | d{ln(Q)}/dt = (dQ/dt)/Q |
Settling rate | s-1 | typically dB/s | [Ratio]/[ΔTime]. Used for transient phenomena |
Relaxation rate | s-1 | | 1/[Relaxation time] |
Frequency of waves | s-1 | Hz | hertz |
Phase drift rate | s-1 | rad.s-1 | [Phase angle]/[Time] |
Angular velocity / speed | s-1 | rad.s-1 | [Plane angle]/[Time] |
Frequency drift rate | s-2 | Hz.s-1 | [ΔFrequency]/[Time]. Applicable to waves |
Angular acceleration / deceleration | s-2 | rad.s-2 | [ΔAngularVelocity]/[Time] |
Quantities related only to space |
Position vector | m | | in all Euclidean n-dimensional spaces |
Length | Distance | m | m | meter |
Perimeter | Circumference | Radius | m | | |
Thickness | m | | usually referred to planar structures |
Wavelength | m | | [Wave velocity]/[Frequency] |
Wavenumber | m-1 | | [Number of waves]/[Distance] |
K-space vector | Reciprocal space position | m-1 | | |
Curvature radius | m | | of a line in plane/space or surface in space |
Curvature | m-1 | | 1/[Curvature radius] |
Convergence | m-1 | dioptry | used in optics, but not only .. |
Attenuation / amplification over a distance | m-1 | dB/m | [Attenuation]/[Distance]. Mostly in acoustic and electronics |
Extinction coefficient | m-1 | dB/m | [Ratio]/m. Used mostly for radiation |
Propagation / transmission loss | m-1 | dB/m | [Ratio]/m. Generic, usable for any quantity |
Area | Cross section | m2 | | [Distance]*[Distance] |
Surface element | Surface area | m2 | | [Distance]*[Distance]. Applicable to 3D bodies |
Volume element | Volume | m3 | | [Area]*[Distance] |
Propagation through space and time |
Velocity | Speed | m.s-1 | | [Distance]/[Time] |
Acceleration | Deceleration | m.s-2 | | [ΔVelocity]/[ΔTime] |
Drift speed | m.s-1 | | Steady-state speed of an object |
Surface / area growth rate | m2.s-1 | | [ΔArea]/[Time] |
Volume growth rate | m3.s-1 | | [ΔVolume]/[Time]. For example, of a crystal |
Volume flow | m3.s-1 | | [Volume]/[Time]. For example, through a device |
Matter distribution and transport |
Particle density | m-3 | | [Count]/[Volume]. Obsolete: number density |
Mass | kg | kg | kilogram |
Mass production rate | kg.s-1 | | [ΔMass]/[Time] |
Mass density | Specific density | kg.m-3 | | [Mass]/[Volume] |
Mass density gradient | Specific density gradient | kg.m-4 | | [Mass density]/[Distance] |
Specific volume | m3.kg-1 | | [Volume]/[Mass] |
Concentration ratio by volume | 1 | Dimensionless | [Partial volume]/[Total volume] |
Concentration ratio by mass | 1 | Dimensionless | [Partial mass]/[Total mass]. Not by weight: obsolete) |
Mass flow (total) | kg.s-1 | | [ΔMass]/[Time]. For example, through a device |
Diffusion coefficient | m2.s-1 | | [Distance2]/[Time] |
Molar distribution and transport quantities: |
Particle count, molar | mol-1 | | [Count]/[Mol]. For example, the Avogadro constant |
Molar production rate | mol.s-1 | | [ΔQuantity]/[Time] |
Molar mass | kg.mol-1 | | [Mass]/[Quantity] |
Molar volume | m3.mol-1 | | [Volume]/[Quantity] |
Molar density | Density of substance | m-3.mol | | [Quantity]/[Volume] |
Molarity | Concentration | m-3.mol | | [Quantity]/[Volume]. Same as molar density |
Molarity gradient | Concentration gradient | m-4.mol | | [Molarity]/[Distance] |
Molar concentration ratio | 1 | Dimensionless | [Partial quantity]/[Total quantity] |
Molality (intended as concentration) | kg-1.mol | mol/kg | [Quantity]/[Mass]. Obsolete |
Katalytic activity | mol.s-1 | katal | [ΔQuantity]/[Time] |
Mechanics and hydrodynamics |
Force | kg.m.s-2 | N | newton. [Mass]*[Acceleration] |
Moment of motion | kg.m.s-1 | | [Mass]*[Velocity], [Mass flow]*[Distance] |
Impulse | kg.m.s-1 | | [ΔMoment of motion], [Force]*[ΔTime], [Mass]*[ΔVelocity] |
Moment of force | Torque | kg.m2.s-2 | N.m | [Force]*[Distance]. Like energy |
Couple | kg.m2.s-2 | N.m | 2*[Force]*[Distance] for two non-aligned opposing forces |
Pressure | kg.m-1.s-2 | N.m-2, Pa | pascal. [Force]/[Area] |
Pressure gradient | kg.m-2.s-2 | N.m-3, Pa/m | [Pressure]/[Distance] |
Energy | Lagrangian | Hamiltonian | kg.m2.s-2 | N.m, J | joule. [Force]*[Distance], [Power]*[Time] |
Specific energy | m2.s-2 | J.kg-1 | [Energy]/[Mass] |
Energy density | kg.m-1.s-2 | J.m-3 | [Energy]/[Volume] |
Power | Energy flux | kg.m2.s-3 | J.s-1, W | watt. [ΔEnergy]/[ΔTime] |
Action | kg.m2.s-1 | J.s | [Energy]*[Time], [Moment of motion]*[Distance] |
Angular moment of inertia | kg.m2 | | [Mass]*[Distance2] |
Angular moment of motion | kg.m2.s-1 | J.s | [Moment of motion]*[Distance] |
Circulation | m2.s-1 | J.s.kg-1 | [Angular moment]/[Mass], [Velocity]*[Loop length] |
Spin | 1 | Dimensionless | of a quantum particle |
Stress | Tension | Compression | kg.m-1.s-2 | N.m-2, Pa (pascal) | [Force]/[Area]. ... same as pressure |
Compressive strength | kg.m-1.s-2 | N.m-2, Pa | [Force]/[Area]. Like pressure |
Strain (mechanical) | 1 | Dimensionless | [ΔLength]/[Length] Relative deformation |
Friction | kg.m.s-2 | N | Tangential force between two moving surfaces |
Traction | kg.m.s-2 | N | Maximum tangential force before slipping |
Velocity, superficial | m.s-1 | m/s | In porous media; as if the space was filled only by the fluid |
Velocity, advection | m.s-1 | m/s | In porous media; actual progress along pressure gradient |
Wave function for N particles (quantum) | m-3N/2 | tentative | |ψ|2dτN is a dimensionless probability element. |
Mechanical and hydrodynamic properties of matter |
Compressibility | Modulus of compression | kg-1.m.s2 | Pa-1 | [Pressure]/([ΔVolume]/[Volume]). Inverse of bulk modulus |
Bulk modulus | kg.m-1.s-2 | N.m-2, Pa | ([ΔVolume]/[Volume])/[Pressure]. Inverse of compressibility |
Young modulus | kg.m-1.s-2 | N.m-2, Pa | [Stress]/[Strain]. Like shear modulus |
Shear modulus | Modulus of rigidity | kg.m-1.s-2 | N.m-2, Pa | [Stress]/[Strain]. Same dimension aas Young modulus |
Poisson's ratio | 1 | Dimensionless | [Transversal striction]/[Londitudinal elongation] |
Impact | Notch resistance | kg.s-2 | J.m-2 | [Energy]/[Area] |
Hardness | Tensile strength | kg.m-1.s-2 | N.m-2, Pa | [Force]/[Area]. Like pressure |
Stiffness (linear) | kg.s-2 | N.m-1 | [Force]/[Displacement]. ... of a structure |
Stiffness (rotational) | kg.m2.s-2.rad-1 | N.m.rad-1 | [Moment of force]/[Angle]. ... of a structure |
Friction coefficient | 1 | Dimensionless | [Tangential force]/[Normal force] |
Traction coefficient | 1 | Dimensionless | [Traction]/[Weight] |
Self-diffusion coefficient | m2.s-1 | | [Distance2]/[Time] |
Surface tension | kg.s-2 | N/m | [Force]/[Length]. Same as surface energy |
Surface energy | kg.s-2 | J/m2 | [Energy]/[Area]. Same as surface tension |
Viscosity, dynamic | kg.m-1.s-1 | Pa.s | ([Force]/[Area])/[ΔVelocity] |
Viscosity, kinematic | m2.s-1 | | [Dynamic viscosity]/[Density] |
Reynolds number | 1 | Dimensionless | [Velocity]*[length]/[Kinematic viscosity] |
Critical angle of repose | rad | or degree | Steepest angle of a slope before a slide |
Porosity, volume | 1 | Dimensionless | [Volume of pores]/[Total volume], in porous media |
Porosity, superficial | 1 | Dimensionless | [Void cross section]/[Total cross section], in porous media |
Permeability, hydraulic | m2 | 1 darcy = 10-12 m2 | [Velocity]*[Viscosity]/[Pressure gradient], in porous media |
Conductivity, hydraulic | m.s-1 | m/s | Used for porous media |
Specific acoustic impedance / resistance / reactance | kg.m-2.s-1 | Pa.s/m , reyl | [ΔPressure]*[Velocity], intensive property |
Specific acoustic conductance / susceptance | kg-1.m2.s | reyl-1 | Inverse of specific acoustic impedance |
Acoustic impedance / resistance / reactance | kg.m-4.s-1 | Pa.s/m3, reyl/m2 | [ΔPressure]/[Volume flow rate], extensive property |
Thermodynamics |
Temperature | K | K | kelvin |
Temperature gradient | Thermal gradient | K.m-1 | | [ΔTemperature]/[Distance] |
Heat | Internal energy | Enthalpy | kg.m2.s-2 | J | Same as energy |
Specific heat | internal energy | enthalpy | m2.s-2 | J.kg-1 | [Heat]/[Mass] |
Heat capacity | kg.m2.s-2.K-1 | J.K-1 | [ΔHeat]/[ΔTemperature] |
Heat flux | kg.m2.s-3 | J.s, W | [ΔHeat]/[ΔTime]. Same as power |
Heat flux density | Irradiance | kg.s-3 | W.m-2 | [Heat flux]/[Area] |
Entropy | kg.m2.s-2.K-1 | J.K-1 | [ΔHeat]/[Temperature] |
Specific entropy | m2.s-2.K-1 | J.K-1.kg-1 | [Entropy]/[Mass] |
Free energy | Free enthalpy | kg.m2.s-2 | J | Helmholtz | Gibbs functions, respectively |
Specific free energy | free enthalpy | m2.s-2 | J.kg-1 | [Energy]/[Mass]. Also specific Helmholtz | Gibbs functions |
Molar thermodynamical quantities: |
Molar heat | internal energy | enthalpy | kg.m2.s-2.mol-1 | J.mol-1 | [Heat]/[Quantity] |
Molar energy | kg.m2.s-2.mol-1 | J.mol-1 | [Energy]/[Quantity] |
Molar entropy | kg.m2.s-2.K-1.mol-1 | J.K-1.mol-1 | [Entropy]/[Quantity] |
Molar free energy | free enthalpy | kg.m2.s-2.mol-1 | J.mol-1 | [Energy]/[Quantity]. Molar versions of the above |
Thermodynamic and thermal properties of matter |
Thermal expansion coefficient | K-1 | | ([ΔLength]/[Length])/[Temperature] |
Heat capacity, specific | m2.s-2.K-1 | J.K-1.kg-1 | [Heat capacity]/[Mass] |
Heat capacity, molar | kg.m2.s-2.K-1.mol-1 | J.K-1.mol-1 | [Heat capacity]/[Quantity] |
Heat of fusion | evaporation, specific | m2.s-2 | J.kg-1 | [Energy]/[Mass] |
Heat of fusion | evaporation, molar | kg.m2.s-2.mol-1 | J.mol-1 | [Energy]/[Quantity] |
Heat conductivity | kg.m.s-3.K-1 | W.m-1.K-1 | [Heat flux]/([Distance]*[ΔTemperature]) |
Thermal diffusivity | m2.s-1 | | ([∂Temp]/[∂Time])/[∇2Temp]. |
Prandtl number | 1 | Dimensionless | [Kinematic viscosity]/[Thermal diffusivity] |
Joule-Thomson coefficient | kg-1.m.s2.K | K.Pa-1 | [ΔTemperature]/[ΔPressure] |
Pi coefficient, molar | kg.m-1.s-2.mol-1 | J.m-3 | [ΔInternalEnergy]/[ΔVolume] |
Chemical potential, molar | kg.m2.s-2.mol-1 | J.mol-1 | [ΔInternalEnergy]/[ΔQuantity] |
Softening point | K | | Temperature at which hardness drops below a level |
Annealing point | K | | Temperature at which viscosity drops below 1012 Pa.s |
Strain point | K | | Temperature at which viscosity drops below 1013.5 Pa.s |
Flash point | K | | Temperature at which vapour can be kept burning |
Fire point | K | | Temperature at which ignited vapour keeps burning |
Thermal properties of devices |
Thermal resistance | kg-1.m-2.s3K | K/W | [ΔT]/[Power]. |
Electromagnetism |
Charge, electric | s.A | C | coulomb. [Current]*[Time] |
Charge density | m-3.s.A | C.m-3 | [Charge]/[Volume] |
Current, electric | A | A | ampere. [Charge]/[Time] |
Current density | Current intensity | m-2.A | | [Current]/[Area] |
Specific charge | Charge/mass ratio | kg-1.s.A | C.kg-1 | [Charge]/[Mass] |
Molar charge | s.A.mol-1 | C.mol-1 | [Charge]/[Quantity] |
Quantum charge | 1 | Dimensionless | [Charge]/[Elementary charge quantum] |
Surface density of charge | m-2.s.A | C.m-2 | [Charge]/[Area] |
Potential, electric | kg.m2.s-3.A-1 | W.A-1, J.C-1, C.F-1, V | volt. [Power]/[Current], [Energy]/[Charge] |
Electric dipole moment | m.s.A | C.m | [Charge]*[Distance] |
Electric quadrupole moment | m2.s.A | C.m2 | [Electric dipole]*[Distance], [Electric charge]*[Distance2] |
Electric field strength | Electric intensity | kg.m.s-3.A-1 | V.m-1 | [ΔPotential]/[Distance] |
Electric field gradient | kg.s-3.A-1 | V.m-2 | [ΔEl.field strength]/[Distance] |
Electric flux density | Electric induction | m-2.s.A | C.m-2 | [Charge]/[Area] |
Electric polarization | Electric displacement | m-2.s.A | C.m-2 | [Charge]/[Area]. Same as electric flux density |
Magnetic field strength | Magnetic intensity | m-1.A | | [Current]/[Distance] |
Magnetic flux | kg.m2.s-2.A-1 | V.s, W.s.A-1, Wb | weber. [ΔPotential]*[Time], [Power]/[dCurrent/dt] |
Magnetic flux density | Magnetic induction | kg.s-2.A-1 | Wb.m-2, T | tesla. [Mag.flux]/[Area] |
Magnetic vector potential | kg.m.s-2.A-1 | m-1.s.V, m.T | [Mag.flux density]*[Distance], [El.field strength]*[Time] |
Magnetization | m-1.A | | [Magnetic moment]/[Volume]. Like magnetic field strength |
Magnetic charge (bound) | m-2.A | | - ∇.[Magnetization] , -Divergence of magnetization |
Poynting vector | kg.s-3 | W.m-2 | [El.field strength]/[Mag.field strength]. Same as irradiance |
Magnetic field gradient | kg.m-1.s-2.A-1 | T.m-1 | [ΔMagnetic flux density]/[Distance] |
Magnetic dipole moment | m2.A | J.T-1 | [Current]*[Area]. Same as magnetic moment |
Magnetic quadrupole moment | m3.A | m.J.T-1 | [Magnetic dipole]*[Distance] |
Gyromagnetic ratio | kg-1.s.A | Hz.T-1 | [Mag.moment]/[Angular moment of motion] |
Magnetogyric ratio | kg.s-1.A-1 | T.Hz-1 | [Angular moment of motion]/[Mag.moment] |
Relativistic four-current (Jα) | m-2.A | | Like current density and [Charge]*[c] |
Relativistic four-potential (Aα) | kg.m.s-2.A-1 | m-1.s.V, m.T | Like magnetic vector potential and [El.potential]/[c] |
Relativistic electromagnetic field tensor (Fμν) | kg.s-2.A-1 | T | Like magnetic flux density |
Relativistic displacement four-tensor (Dμν) | m-1.A | | Like magnetic intensity |
Electromagnetic properties of matter |
Resistivity | kg.m3.s-3.A-2 | Ω.m | [Resistance]*[Length])/[Area] |
Conductivity | kg-1.m-3.s3.A2 | S.m-1 | 1/[Resistivity] |
Permittivity, electric | kg-1.m-3.s4.A2 | F.m-1 | [El.flux density]/[El.field strength] |
Dielectric constant | Relative permittivity | 1 | Dimensionless | [Permittivity]/[Permittivity of vacuum] |
Permeability, magnetic | kg.m.s-2.A-2 | N.A-2, H.m-1 | [Mag.flux density]/[Mag.field strength] |
Reluctance, magnetic | kg-1.m-1.s2.A2 | m.H-1 | 1/[Permeability] |
Relative permeability, magnetic | 1 | Dimensionless | [Permeability]/[Permeability of vacuum] |
Susceptibility, magnetic | 1 | Dimensionless | [Relative permeability] - 1 |
Characteristic impedance | kg.m2.s-3.A-2 | V.A-1, Ω, ohm | √([Mag.Permeability]/[El.Permittivity]) |
Electric | Dielectric strength | rigidity | kg.m.s-3.A-1 | V.m-1 | [ΔPotential]/[Distance] |
Verdet constant | kg-1.m-1.s2.A1 | rad.m-1.T-1 | ([Angle]/[Length])/[Magnetic flux density] |
Work function | kg.m2.s-2 | J, eV | [Energy] needed to remove an electron |
Thermoelectric power | Thermopower | kg.m2.s-3.A-1.K-1 | V.K-1 | [ΔPotential]/[ΔTemperature] |
Seeback coefficient | kg.m2.s-3.A-1.K-1 | V.K-1 | [ΔPotential]/[ΔTemperature] |
Thomson coefficient | kg.m2.s-3.A-1.K-1 | W.K-1.A-1 | [Heat flux]/([ΔTemperature]*[Current]) |
Peltier coefficient | kg.m2.s-3.A-1 | W.A-1, V | [Heat flux]/[Current] |
Piezzoelectric coefficient | kg.m.s-3.A-1 | V.m-1 | [El.field strength]/([ΔLength]/[Length]) |
Electrostriction coefficient | kg-2.m-2.s6.A2 | m2.V-2 | ([ΔVolume]/[Volume])/[El.field strength]2 |
g-factor of a particle | 1 | Dimensionless | [Mag.moment]/([Spin].[Bohr magneton]) |
Properties of electric/magnetic devices and circuit components |
Bandwidth | s-1 | Hz | [ΔFrequency] |
Voltage | Electromotive force (emf) | kg.m2.s-3.A-1 | V | [ΔPotential] |
Current, electric | A | A | ampere. [Charge]/[Time] |
Magnetomotive force (mmf) | A | | [Current]*[Number of turns] |
Impedance, of a circuit | kg.m2.s-3.A-2 | Ω | ohm |
Admittance, of a circuit | kg-1.m-2.s3.A2 | S | siemens. 1/[Circuit impedance] |
Resistance | kg.m2.s-3.A-2 | V.A-1, Ω(ohm) | [ΔPotential]/[Current] |
Conductance | kg-1.m-2.s3.A2 | A.V-1, S (siemens) | 1/[Resistance] |
Capacitance | kg-1.m-2.s4.A2 | C.V-1, F | farad. [Charge]/[ΔPotential] |
Reactance, capacitive | kg.m2.s-3.A-2 | Ω (ohm) | 1/(i[Angular frequency].[Capacitance]) |
Susceptance, capacitive | kg-1.m-2.s3.A2 | S (siemens) | 1/[Reactance] |
Inductance | Mutual inductance | kg.m2.s-2.A-2 | V.s.A-1, Wb.A-1, H | henry. [ΔPotential]/[dCurrent/dt] or [Magnetic flux]/[Current] |
Impedance, inductive | kg.m2.s-3.A-2 | Ω (ohm) | i[Angular frequency].[Inductance] |
Admittance, inductive | kg-1.m-2.s3.A2 | S (siemens) | 1/[Inductive impedance] |
Number of turns | 1 | | Applicable to coils, transformers, etc |
Current noise, variance nJ2 | s.A2 | A2/Hz | [Current]2/[Bandwidth] |
Voltage noise, variance nV2 | kg2.m4.s-5.A-2 | V2/Hz | [Voltage]2/[Bandwidth] |
Chemistry, physical chemistry, atomic and molecular physics |
Concentration | Molar density | Molarity | m-3.mol | | [Quantity]/[Volume]. Same as Density of substance |
Molality | kg-1.mol | mol/kg | [Quantity]/[Mass] |
Katalytic activity | Molar production rate | mol.s-1 | katal | [Quantity]/[Time] |
Molar mass | kg.mol-1 | | [Mass]/[Quantity] |
Molar charge | s.A.mol-1 | C.mol-1 | [Charge]/[Quantity] |
Molecular | ionic quantum charge | 1 | Dimensionless | [Charge of a molecule or ion]/[Elementary charge quantum] |
Ionic strength | Ionic force | m-3.mol | | Sum([Conc.]*[Ionic quantum charge]2) |
Ion mobility | kg-1.m-1.s2.A | m2.s-1.V-1 | [Velocity]/[Electric field strength] . |
Drift speed | m.s-1 | | Steady-state speed of ions in electric field . |
Fugacity | kg.m-1.s-2 | Pa | Effective pressure in real gases |
Osmotic pressure | kg.m-1.s-2 | Pa | |
Thermodynamic force | kg.m.s-2.mol-1 | N/mol | [ΔChemical potential]/[Distance] |
Chemico-physical properties of elements |
Atomic number | 1 | Dimensionless | Number of protons in an atomic nucleus |
Atomic weight | Relative atomic mass | au | atomic units | Average over a typical isotopic composition |
Mass number of an isotope | 1 | Dimensionless | Number of protons+neutrons in the isotope nuclide |
Electronegativity, Pauling χ | 1 | Dimensionless | Relative tendency of an atom to attract electrons; χ(H)=2.20. |
Electron affinity (always molar) | kg.m2.s-2.mol-1 | J.mol-1 | Energy released when binding an electron |
Chemico-physical properties of matter |
Ionization energy, molar | kg.m2.s-2.mol-1 | J.mol-1 | Energy to ionize a molecule/atom |
Volume, molar | m3.mol-1 | | [Volume]/[Quantity] |
Heat of fusion | evaporation, molar | kg.m2.s-2.mol-1 | J.mol-1 | [Energy]/[Quantity] |
Chemical potential, molar | kg.m2.s-2.mol-1 | J.mol-1 | [ΔInternalEnergy]/[ΔQuantity] |
Solubility, molar | m-3.mol | | [Quantity]/[Volume] |
Reduction | Redox potential | kg.m2.s-3.A-1 | V (volt) | |
Conductivity, molar | kg-1.s3.A2.mol-1 | S.m2.mol-1 | [El.conductivity]/[Concentration] |
Relaxivity, molar | s-1.mol-1 | | [Relaxation rate]/[Concentration] |
Ebullioscopic constant | kg.mol-1.K | K/(mol/kg) | [ΔTemperature]/[Molality] |
Cryoscopic constant | kg.mol-1.K | K/(mol/kg) | [ΔTemperature]/[Molality] |
Compression factor of a real gas | 1 | Dimensionless | pV/(nRT). For ideal gas equals 1; temperature dependent |
van der Waals constant: a | kg.m5.s-2.mol-2 | Pa.m6 | a in (p+a/V2)(V-b)=RT, where V is molar volume |
van der Waals constant: b | m3.mol-1 | | b in (p+a/V2)(V-b)=RT, where V is molar volume |
Virial coefficient: second | m3.mol-1 | | B in pV/(nRT)=1+B(n/V)+C(n/V)2+D(n/V)3+... |
Virial coefficient: third | m6.mol-2 | | C in pV/(nRT)=1+B(n/V)+C(n/V)2+D(n/V)3+... |
Virial coefficient: fourth | m9.mol-3 | | C in pV/(nRT)=1+B(n/V)+C(n/V)2+D(n/V)3+... |
Gravitation, Astronomy, Cosmology |
Gravitational field intensity | Gravity | m.s-2 | | [Force]/[Mass], Same as acceleration |
Gravitational field potential | m2.s-2 | | [Energy]/[Mass] |
Gravitational constant G | kg-1.m3.s-2 | | [Force]*[Distance]2/[Mass]2. Appears in Newton's equation |
Mean motion | s-1 | | Of a body on a Kepler orbit; sqrt(G(M1+M2)/r3) |
Mean anomaly | 1 | Dimensionless | Of a body on a Kepler orbit; t.sqrt(G(M1+M2)/r3) |
Star magnitude (astronomy) | 1 | Dimensionless | m-m'= -100.4(S/S'). S,S' are luminous fluxes of two stars |
Cosmological constant Λ | m-2 | | Appears in Einstein's equation |
Cosmological expansion rate | s-1 | km/s/Mpc | [Velocity]/[Distance]. Mpc stands for Megaparsec |
Optics |
Albedo, of a surface | 1 | Dimensionless | [Reflected elmag power]/[Incident elmag power] |
Convergence | m-1 | dioptry | dioptry |
Luminosity | Luminous intensity | cd | cd | candle or lumen/sr |
Luminous flux | Luminous power | cd.sr | lm | lumen. [Luminosity]*[Solid angle] |
Luminance | cd.m-2 | | [Luminosity]/[Area] |
Luminous energy | cd.sr.s | lm.s | [Luminous flux]*[Time]. Also known as talbot |
Illuminance | cd.sr.m-2 | lm.m-2, lx | lux. [Luminous flux]/[Area] |
Luminous emittance | cd.sr.m-2 | lm.m-2, lx | lux. Same as illuminance, but for sources |
Luminous efficacy | cd.sr.kg-1.m-1.s3 | lm/W | [Luminous flux]/[Power] |
Luminous efficiency | Luminous coefficient | 1 | Dimensionless | [Luminous efficacy]/[683 lm/W] |
Irradiance | kg.s-3 | W.m-2 | [Power]/[Area]. For all kinds of energy deposition |
Radiance | kg.s-3.sr-1 | W.m-2.sr-1 | ([Power]/[Area])/[Solid angle] |
Optical properties of matter |
Extinction coefficient | m-1 | | |
Refractive index | 1 | Dimensionless | Light speeds ratio (in medium)/(in vacuum) |
Specific refractivity | m3.kg-1 | | [(r2-1)/(r2+2)]/[Specific density], where r is refractive index |
Molar refractivity | m3.mol-1 | | [(r2-1)/(r2+2)]/[Concentration] |
Dispersivity quotient | m-1 | | [ΔRefractive index]/[ΔWavelength] |
Dispersive power | 1 | Dimensionless | Ratio of differences of refractive indices |
Constringence | Abbé number | V-number | 1 | Dimensionless | VD = (nD-1)/(nF-nC) |
Radiation and radioactivity |
Radioactivity | Activity | s-1 | Bq | bequerel. [Counts]/[Time] |
Irradiance | kg.s-3 | W.m-2 | [Power]/[Area]. For all kinds of energy deposition |
Absorbed dose | m2.s-2 | J.kg-1, Gy | gray. [Energy]/[Mass] |
Absorbed dose rate | m2.s-3 | Gy.s-1 | [Absorbed dose]/[Time] |
Absorbed dose equivalent | m2.s-2 | J.kg-1, Sv | sievert. [const].[Energy]/[Mass] |
Exposure | kg-1.s.A | C.kg-1 | [Charge]/[Mass]. For ionising radiations |
Radiation properties of matter |
Half life | s | | Of a radioisotope |
Radiation power | m2.s-3 | W/kg | [Power]/[Mass]. Heat generated by a radioisotope |
Radiation power, molar | kg.m2.s-3.mol-1 | W/mol | [Power]/[Quantity]. Heat generated by a radioisotope |
Informatics |
Information | bit-1 | bit | bit; the elementary information quantum |
Baud rate | Information flux | bit.s-1 | Baud | baud. [Information]/[Time] |
Economy and finance |
Transactions count | 1 | Dimensionless | All kinds of counts |
Interest | 1 | % | [ΔWealth]/[Wealth]. Usually expressed as percentage |
Wealth | Asset | cur | currency | Currencies like $, EUR, Yuan, ... are different units |
Debt | Liability | cur | currency | Usually intended as negative wealth |
Value | Price | cur | currency | Prefixes: K..thousands, M..millions, B..billions |
Transaction value | Sale | Purchase | cur | currency | Often used: mean and total values |
Time period | s | year,quarter,month | Abbrevs: mrq.. most recent quarter, ttm.. trailing twelve months |
Fiscal year | Calendar year | s | year | Abbrevs: lfy.. last fiscal year, yoy.. year over year |
Transactions rate | Activity | s-1 | 1/year | [Transactions]/[Time period] |
Transactions volume | Sales flow | cur.s-1 | | [Value]/[Time period]. For example $/day or Eur/year |
Velocity / circulation of money | s-1 | 1/year | [Transactions]/[Time period] |
Interest rate | s-1 | %/year | [Interest]/[Time period] |
Return on asset / equity | s-1 | %/year | ([ΔValue]/[Value])/[Time period] |
Cash flow | Flow (generic) | cur.s-1 | currency/year | [Value]/[ΔTime]. Mathematically, time derivative |
Earnings | Income rate | cur.s-1 | currency/year | [Value]/[Time period] |
GDP Gross domestic product | cur.s-1 | currency/year | [Earnings]. Usually refered to nations/states/admin.regions |
Debt/GDP ratio | s | year | [Debt]/[Earnings]. Independent of currency / population size |
P/E Price/Earnings ratio | s | year | [Value]/[Earnings]. Used to assess an asset/company |
Bond duration | s | year | In general, the duration of a fixed cash flow |
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