Physics:List of common physics notations

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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
[math]\displaystyle{ \mathbf{A} }[/math] magnetic vector potential tesla meter (T⋅m)
[math]\displaystyle{ A }[/math] area square meters (m2)
amplitude meter
atomic mass number unitless
[math]\displaystyle{ \mathbf{a} }[/math] acceleration meters per second squared (m/s2)
[math]\displaystyle{ \mathbf{B} }[/math] magnetic flux density
also called the magnetic field density or magnetic induction
tesla (T), or equivalently,
weber per square meter (Wb/m2)
[math]\displaystyle{ C }[/math] capacitance farad (F)
heat capacity joule per kelvin (J⋅K−1)
constant of integration varied depending on context
[math]\displaystyle{ c }[/math] speed of light (in vacuum) 299,792,458 meters per second (m/s)
speed of sound meters 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)
[math]\displaystyle{ \mathbf{D} }[/math] electric displacement field
also called the electric flux density
coulomb per square meter (C/m2)
[math]\displaystyle{ D }[/math] density kilograms per cubic meter (kg/m3)
diameter meter (m)
[math]\displaystyle{ d }[/math] distance meter (m)
direction unitless
impact parameter meter (m)
differential (e.g. [math]\displaystyle{ dx }[/math]) varied depending on context
[math]\displaystyle{ d\mathbf{A} }[/math] differential vector element of surface area A, with infinitesimally small magnitude and direction normal to surface S square meter (m2)
[math]\displaystyle{ dV }[/math] differential element of volume V enclosed by surface S cubic meter (m3)
[math]\displaystyle{ \mathbf{E} }[/math] electric field newton per coulomb (N⋅C−1), or equivalently, volt per meter (V⋅m−1)
[math]\displaystyle{ E }[/math] energy joule (J)
Young's modulus pascal (Pa) or newton per square meter (N/m2)
[math]\displaystyle{ e }[/math] eccentricity unitless
2.71828... (base of the natural logarithm) unitless
electron unitless
elementary charge coulomb (C)
[math]\displaystyle{ \mathbf{F} }[/math] force newton (N)
[math]\displaystyle{ F }[/math] Faraday constant coulombs per mole (C⋅mol−1)
[math]\displaystyle{ f }[/math] frequency hertz (Hz)
function
friction newton (N)
[math]\displaystyle{ G }[/math] 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)
[math]\displaystyle{ \mathbf{g} }[/math] acceleration due to gravity meters per second squared (m/s2), or equivalently, newtons per kilogram (N/kg)
[math]\displaystyle{ \mathbf{H} }[/math] magnetic field strength ampere per meter (A/m)
[math]\displaystyle{ H }[/math] Hamiltonian joule (J)
enthalpy joule (J)
thermal current watt (W)
[math]\displaystyle{ h }[/math] height meter (m)
Planck constant joule second (J⋅s)
[math]\displaystyle{ \hbar }[/math] reduced Planck constant joule second (J⋅s)
[math]\displaystyle{ I }[/math] 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)
[math]\displaystyle{ i }[/math] intensity watt per square meter (W/m2)
imaginary unit unitless
electric current ampere (A)
[math]\displaystyle{ \mathbf{\hat{\imath}} }[/math] Cartesian x-axis basis unit vector unitless
[math]\displaystyle{ \mathbf{J} }[/math] current density ampere per square meter (A/m2)
impulse kilogram meter per second (kg⋅m/s)
[math]\displaystyle{ \mathbf{j} }[/math] jerk meters per second cubed (m/s3)
[math]\displaystyle{ j }[/math] imaginary unit (electrical) unitless
[math]\displaystyle{ \mathbf{\hat{\jmath}} }[/math] Cartesian y-axis basis unit vector unitless
[math]\displaystyle{ K }[/math] kinetic energy joule (J)
[math]\displaystyle{ \mathbf{k} }[/math] wave vector radians per meter (m−1)
[math]\displaystyle{ k }[/math] Boltzmann constant joule per kelvin (J/K)
wavenumber radians per meter (m−1)
stiffness newtons per meter (N⋅m−1)
[math]\displaystyle{ \mathbf{\hat{k}} }[/math] Cartesian z-axis basis unit vector unitless
[math]\displaystyle{ \mathbf{L} }[/math] angular momentum newton meter second (N⋅m⋅s or kg⋅m2⋅s−1)
[math]\displaystyle{ L }[/math] inductance henry (H)
luminosity watt (W)
Lagrangian joule (J)
[math]\displaystyle{ l }[/math] length meter (m)
azimuthal quantum number unitless
[math]\displaystyle{ \mathbf{M} }[/math] magnetization amperes per meter (A/m)
[math]\displaystyle{ M }[/math] moment of force
often simply called moment or torque
newton meter (N⋅m)
[math]\displaystyle{ m }[/math] mass kilogram (kg)
[math]\displaystyle{ \mathbf{N} }[/math] normal vector unit varies depending on context
[math]\displaystyle{ N }[/math] atomic number unitless
[math]\displaystyle{ n }[/math] refractive index unitless
principal quantum number unitless
amount of substance mole
[math]\displaystyle{ P }[/math] power watt (W)
probability unitless
[math]\displaystyle{ \mathbf{p} }[/math] momentum kilogram meter per second (kg⋅m/s)
[math]\displaystyle{ p }[/math] pressure pascal (Pa)
[math]\displaystyle{ Q }[/math] electric charge coulomb (C)
heat joule (J)
[math]\displaystyle{ q }[/math] electric charge coulomb (C)
[math]\displaystyle{ R }[/math] 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)
[math]\displaystyle{ \mathbf{r} }[/math] radius vector (position) meter (m)
[math]\displaystyle{ r }[/math] radius or distance meter (m)
[math]\displaystyle{ S }[/math] surface area m2
entropy joule per kelvin (J/K)
action joule second (J⋅s)
[math]\displaystyle{ \mathbf{s} }[/math] displacement meter (m)
[math]\displaystyle{ s }[/math] arc length meter (m)
distance meter (m)
[math]\displaystyle{ T }[/math] period second (s)
temperature kelvin (K) or Celsius (C)
kinetic energy joule (J)
[math]\displaystyle{ t }[/math] time second (s)
[math]\displaystyle{ \mathbf{U} }[/math] four-velocity meter per second (m/s)
[math]\displaystyle{ U }[/math] potential energy joule (J)
internal energy joule (J)
[math]\displaystyle{ u }[/math] relativistic mass kilogram (kg)
energy density joule per cubic meter (J/m3)
specific energy joule per kilogram (J/kg)
[math]\displaystyle{ V }[/math] voltage
also called electric potential difference
volt (V)
volume cubic meter (m3)
shear force
[math]\displaystyle{ \mathbf{v} }[/math] velocity meter per second (m/s)
[math]\displaystyle{ W }[/math] weight newton (N)
mechanical work joule (J)
[math]\displaystyle{ w }[/math] width meter (m)
[math]\displaystyle{ X }[/math] electrical reactance ohm (Ω)
[math]\displaystyle{ \mathbf{x} }[/math] position vector meter (m)
displacement meter (m)
[math]\displaystyle{ x }[/math] a generic unknown varied depending on context
[math]\displaystyle{ Y }[/math] admittance siemens (S)
[math]\displaystyle{ Z }[/math] compressibility factor unitless
electrical impedance ohm (Ω)
[math]\displaystyle{ Z_0 }[/math] impedance of free space ohm (Ω)

Greek characters

Symbol Name Meaning SI unit of measure
[math]\displaystyle{ \alpha }[/math] alpha alpha particle
angular acceleration radian per second squared (rad/s2)
fine-structure constant unitless
[math]\displaystyle{ \beta }[/math] beta velocity in terms of the speed of light c unitless
beta particle
[math]\displaystyle{ \gamma }[/math] gamma Lorentz factor unitless
photon
gamma ray
shear strain radian
heat capacity ratio unitless
surface tension newton per meter (N/m)
[math]\displaystyle{ \Delta }[/math] delta change in a variable (e.g. [math]\displaystyle{ \Delta x }[/math]) unitless
Laplace operator per square meter (m−2)
[math]\displaystyle{ \delta }[/math] displacement (usually small) meter (m)
Dirac delta function
Kronecker delta (e.g [math]\displaystyle{ \delta_{ij} }[/math])
[math]\displaystyle{ \epsilon }[/math] epsilon permittivity farad per meter (F/m)
strain unitless
[math]\displaystyle{ \varepsilon_0 }[/math] epsilon nought vacuum permittivity constant farad per meter (F/m)
[math]\displaystyle{ \zeta }[/math] zeta damping ratio unitless
[math]\displaystyle{ \eta }[/math] eta angular jerk radians per second cubed (rad⋅s−3)
energy efficiency unitless
(dynamic) viscosity (also [math]\displaystyle{ \mu }[/math]) pascal second (Pa⋅s)
[math]\displaystyle{ \theta }[/math] theta angular displacement radian (rad)
[math]\displaystyle{ \kappa }[/math] kappa torsion coefficient
also called torsion constant
newton meter per radian (N⋅m/rad)
[math]\displaystyle{ \Lambda }[/math] lambda cosmological constant per second squared (s−2)
[math]\displaystyle{ \lambda }[/math] wavelength meter (m)
linear charge density coulomb per meter (C/m)
eigenvalue non-zero vector
[math]\displaystyle{ \mathbf{\mu} }[/math] mu magnetic moment ampere square meter (A⋅m2)
coefficient of friction unitless
(dynamic) viscosity (also [math]\displaystyle{ \eta }[/math]) pascal second (Pa⋅s)
permeability (electromagnetism) henry per meter (H/m)
reduced mass kilogram (kg)
gravitational parameter cubic meter per second squared
[math]\displaystyle{ \mathbf{\mu}_0 }[/math] mu nought vacuum permeability constant or magnetic constant henry per meter (H/m)
[math]\displaystyle{ \nu }[/math] nu frequency hertz (Hz)
kinematic viscosity meters squared per second (m2/s)
neutrino
[math]\displaystyle{ \xi }[/math] xi electromotive force volt (V)
[math]\displaystyle{ \pi }[/math] pi 3.14159... (irrational number) unitless
[math]\displaystyle{ \rho }[/math] 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)
[math]\displaystyle{ \Sigma }[/math] sigma summation operator
[math]\displaystyle{ \sigma }[/math] 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)
[math]\displaystyle{ \tau }[/math] tau torque newton meter (N⋅m)
shear stress pascal (Pa)
time constant second (s)
6.28318... () unitless
[math]\displaystyle{ \Phi }[/math] phi field strength unit varies depending on context
magnetic flux weber (Wb)
[math]\displaystyle{ \phi }[/math] electric potential volt (V)
Higgs field work function
[math]\displaystyle{ \Psi }[/math] psi wave function m−3/2
[math]\displaystyle{ \Omega }[/math] omega electric resistance ohm
[math]\displaystyle{ \omega }[/math] angular frequency radian per second (rad/s)
angular velocity radian per second (rad/s)
integral the inverse of the derivative. unitless

Other characters

Symbol Name Meaning SI unit of measure
[math]\displaystyle{ \nabla\cdot }[/math] nabla dot the divergence operator
often pronounced "del dot"
per meter (m−1)
[math]\displaystyle{ \nabla\times }[/math] nabla cross the curl operator
often pronounced "del cross"
per meter (m−1)
[math]\displaystyle{ \nabla }[/math] nabla delta (differential operator)
[math]\displaystyle{ \partial }[/math] "der", "dow", "die", "partial" or simply "d" partial derivative (e.g. [math]\displaystyle{ \partial y/\partial x }[/math])
[math]\displaystyle{ \Box }[/math] D'Alembert operator [math]\displaystyle{ \nabla^2-\partial_t^2 }[/math]
[math]\displaystyle{ \langle \, \, \rangle }[/math] angle brackets average

sometimes over Maxwell–Boltzmann distribution

[math]\displaystyle{ \langle \ | \ \rangle }[/math] Dirac notation

See also

References