This is a list of common physical constants and variables, and their notations. Note that bold text indicates that the quantity is a vector.

Latin characters

Symbol Meaning SI unit of measure magnetic vector potential tesla meter (T⋅m) area square meter (m2) amplitude meter atomic mass number unitless acceleration meter per second squared (m/s2) magnetic flux density also called the magnetic field density or magnetic induction tesla (T), or equivalently, weber per square meter (Wb/m2) capacitance farad (F) heat capacity joule per kelvin (J⋅K−1) constant of integration varied depending on context speed of light (in vacuum) 299,792,458 meters per second (m/s) speed of sound meter per second (m/s) specific heat capacity joule per kilogram per kelvin (J⋅kg−1⋅K−1) viscous damping coefficient kilogram per second (kg/s) electric displacement field also called the electric flux density coulomb per square meter (C/m2) density kilogram per cubic meter (kg/m3) diameter meter (m) distance meter (m) direction unitless impact parameter meter (m) differential (e.g. ) varied depending on context differential vector element of surface area A, with infinitesimally small magnitude and direction normal to surface S square meter (m2) differential element of volume V enclosed by surface S cubic meter (m3) electric field newton per coulomb (N⋅C−1), or equivalently, volt per meter (V⋅m−1) energy joule (J) Young's modulus pascal (Pa) or newton per square meter (N/m2) eccentricity unitless Euler's number (2.71828, base of the natural logarithm)unitless electron unitless elementary charge coulomb (C) force newton (N) Faraday constant coulombs per mole (C⋅mol−1) frequency hertz (Hz) functionunitless friction newton (N) electrical conductance siemens (S) universal gravitational constant newton meter squared per kilogram squared (N⋅m2/kg2) shear modulus pascal (Pa) or newton per square meter (N/m2) gluon field strength tensor inverse length squared (1/m2) acceleration due to gravity meters per second squared (m/s2), or equivalently, newtons per kilogram (N/kg) magnetic field strength ampere per meter (A/m) Hamiltonian joule (J) enthalpy joule (J)thermal currentwatt (W) height meter (m) Planck constant joule second (J⋅s) reduced Planck constant joule second (J⋅s) action joule second (J⋅s) intensity watt per square meter (W/m2) sound intensity watt per square meter (W/m2) electric current ampere (A) moment of inertia kilogram meter squared (kg⋅m2) intensity watt per square meter (W/m2) imaginary unit unitless electric current ampere (A) Cartesian x-axis basis unit vector unitless current density ampere per square meter (A/m2) impulse kilogram meter per second (kg⋅m/s) jerk meter per second cubed (m/s3) imaginary unit (electrical) unitless Cartesian y-axis basis unit vector unitless kinetic energy joule (J) wave vector radian per meter (m−1) Boltzmann constant joule per kelvin (J/K) wavenumber radian per meter (m−1) stiffness newton per meter (N⋅m−1) Cartesian z-axis basis unit vector unitless angular momentum newton meter second (N⋅m⋅s or kg⋅m2⋅s−1) inductance henry (H) luminosity watt (W) Lagrangian joule (J) Lagrangian density joule per cubic meter (J/m3) length meter (m) ℓ azimuthal quantum number unitless magnetization ampere per meter (A/m) moment of force often simply called moment or torque newton meter (N⋅m) mass kilogram (kg) normal vector unit varies depending on context neutron number unitless refractive index unitless principal quantum number unitless amount of substance mole power watt (W)active power (real power)watt (W) probability unitless momentum kilogram meter per second (kg⋅m/s) pressure pascal (Pa) electric charge coulomb (C) heat joule (J)Reactive Powervolt-ampere reactive (var) Generalized coordinates varied depending on context (sometimes meter (m) or radian (rad)) electric charge coulomb (C) electrical resistance ohm (Ω) Ricci tensor reciprocal square meter (m−2) radiancy meter per second gas constant joule per mole per kelvin (J⋅mol−1⋅K−1) radius vector (position) meter (m) radius or distance meter (m) surface area square meter (m2) entropy joule per kelvin (J/K) action joule second (J⋅s)apparent power (complex power)Volt-Ampere (VA) displacement meter (m) arc length meter (m) distance meter (m) period second (s) temperature kelvin (K) or Celsius (C) kinetic energy joule (J) time second (s) four-velocity meter per second (m/s) potential energy joule (J) internal energy joule (J)uinitial velocitymeter per second (m/s) relativistic mass kilogram (kg) energy density joule per cubic meter (J/m3) specific energy joule per kilogram (J/kg) voltage also called electric potential difference volt (V) volume cubic meter (m3) shear forcenewton (N) velocity meter per second (m/s) weight newton (N) mechanical work joule (J) width meter (m) electrical reactance ohm (Ω) position vector meter (m) displacement meter (m) a generic unknown varied depending on context admittance siemens (S) atomic number unitless compressibility factor unitless electrical impedance ohm (Ω) impedance of free space ohm (Ω)

Greek characters

Symbol Name Meaning SI unit of measurealpha alpha particle angular acceleration radian per second squared (rad/s2) fine-structure constant unitlessbeta velocity in terms of the speed of light c unitless beta particle gamma Lorentz factor unitless photon gamma ray shear strain radian heat capacity ratio unitless surface tension newton per meter (N/m) delta change in a variable (e.g. ) unitless Laplace operator per square meter (m−2) displacement (usually small) meter (m) Dirac delta function Kronecker delta (e.g ) epsilon permittivity farad per meter (F/m) strain unitlessepsilon nought Vacuum permittivity farad per meter (F/m) zeta damping ratio unitless eta angular jerk radian per second cubed (rad⋅s−3) energy efficiency unitless (dynamic) viscosity (also ) pascal second (Pa⋅s) theta angular displacement radian (rad) kappa torsion coefficient also called torsion constant newton meter per radian (N⋅m/rad) lambda cosmological constant per second squared (s−2) wavelength meter (m) linear charge density coulomb per meter (C/m) eigenvalue non-zero vectormu magnetic moment ampere square meter (A⋅m2) coefficient of friction unitless (dynamic) viscosity (also ) pascal second (Pa⋅s) permeability (electromagnetism) henry per meter (H/m) reduced mass kilogram (kg) Standard gravitational parameter cubic meter per second squaredmu nought Vacuum permeability or the magnetic constant henry per meter (H/m) nu frequency hertz (Hz) kinematic viscosity meter squared per second (m2/s) neutrino xi electromotive force volt (V) pi 3.14159... (irrational number) unitless rho mass density usually simply called density kilogram per cubic meter (kg/m3) volume charge density coulomb per cubic meter (C/m3) resistivity ohm meter (Ω⋅m) sigma summation operator area charge density coulomb per square meter (C/m2) electrical conductivity siemens per meter (S/m) normal stress pascal (Pa) scattering cross section barn (10^-28 m^2) surface tension newton per meter (N/m) tau torque newton meter (N⋅m) shear stress pascal (Pa) time constant second (s) 6.28318... (2π) unitless phi field strength unit varies depending on context magnetic flux weber (Wb) electric potential volt (V) Higgs field work function psi wave function m−3/2omega electric resistance ohm angular frequency radian per second (rad/s)angular velocityradian per second (rad/s)

Other characters

Symbol Name Meaning SI unit of measure nabla dot the divergence operator often pronounced "del dot" per meter (m−1) nabla cross the curl operator often pronounced "del cross" per meter (m−1) nabla the gradient operator per meter (m−1) "der", "dow", "die", "partial" or simply "d"partial derivative (e.g. ) D'Alembert operator angle brackets average sometimes over Maxwell–Boltzmann distribution Dirac notation integralthe inverse of the derivative.unitless

See also List of letters used in mathematics and science Glossary of mathematical symbols List of mathematical uses of Latin letters Greek letters used in mathematics, science, and engineering Physical constant Physical quantity International System of Units ISO 31

References