Physics Symbols

Physics Symbols List and Their Names

In physics, there are a large number of physical quantities we include while performing calculations. To make it more convenient for users and easier to use and remember, we often use notations/symbols to represent these physical quantities. These notations/symbols we use to represent physical quantities when solving problems related to them or for other purposes are symbols.

The symbols used for physical quantities are vastly different. Sometimes, the symbol may be the first letter of the physical quantities they represent, like, which stands for distance. Other times, they may be completely unrelated to the name of the physical quantities, like c, which stands for the speed of light. They may also be in the form of Greek characters, like λ, which stands for wavelength.

Below are some symbols used commonly in physics with their names, the type of quantities and their SI units.

Symbols used to denote physical quantities related to space and time:
SymbolQuantity/ CoefficientsS.I UnitPhysical Quantity (Scalar/Vector)
rRadius, the radius of curvatureMeterFunctions as both scalar and vector
θ, φAngular displacement, angular separation, the rotational angleMeterFunctions as both scalar and vector
x, y, zCartesian coordinatesUnitlessScalar
î, ĵ, k̂Cartesian unit vectorsUnitlessVector
r, θ, φSpherical coordinatesMeter/RadianScalar
r̂, θ̂, φ̂Spherical unit vectorsUnitlessVector
r, θ, zCylindrical coordinatesMeter/RadianScalar
r̂, θ̂, ẑCylindrical unit vectorsUnitlessVector
Normal unit vectorUnitlessVector
Tangential unit vectorUnitlessVector
hHeight, depthMeterScalar
ℓ, LLengthMeterScalar
A, AAreaSquare meterFunctions as both scalar and vector
VVolumeCubic meterScalar
tTime, durationSecondScalar
TPeriodic timeSecondScalar
τTime ConstantSecondScalar
ωAngular frequencyRadian per secondScalar

Symbols used to denote physical quantities related to Mechanics:
SymbolQuantity/ CoefficientsS.I UnitPhysical Quantity (Scalar/Vector)
vVelocity, speedmeter per secondFunctions as vector
aAccelerationmeter per second squaredFunctions as and vector
acCentripetal/Centrifugal accelerationmeter per second squaredFunctions as vector
gAcceleration due to gravitymeter per second squaredFunctions vector
FForceNewtonFunctions as vector
Fg /WForce due to gravity/WeightNewtonFunctions as vector
Fn, NNormal force, normalNewtonFunctions as vector
FfForce of frictionNewtonFunctions as vector
µCoefficient of frictionUnitlessScalar
pMomentumKilogram meter per secondFunctions as vector
JImpulseNewton secondFunctions as vector
KKinetic energyJouleScalar
UPotential energyJouleScalar
VgGravitational potentialJoule per kilogramScalar
ωRotational speed, rotational velocityRadian per secondFunctions as vector
αRotational accelerationRadian per second squaredFunctions as vector
τTorqueNewton meterFunctions as vector
IMoment of inertiaKilogram meter squaredScalar
LAngular momentumKilogram meter squared per secondFunctions as vector
HAngular impulseNewton meter secondFunctions as vector
kSpring constantNewton per meterScalar
τShear stressPascalScalar
ρDensity, volume mass densityKilogram per cubic meterScalar
σArea mass densityKilogram per square meterScalar
λLinear mass densityKilogram per meterScalar
FB, BBuoyancyNewtonFunctions as vector
qmMass flow rateKilogram per secondScalar
qVVolume flow rateCubic meter per secondScalar
FD, RDrag or air resistanceNewtonFunctions as vector
CD Drag coefficientUnitlessScalar
νKinematic viscositySquare meter per secondScalar
MaMach numberUnitlessScalar
ReReynolds numberUnitlessScalar
FrFroude numberUnitlessScalar
EYoung’s modulus of elasticityPascalScalar
GShear modulus of rigidityPascalScalar
KBulk modulus of compressionPascalScalar
εLinear strainUnitlessScalar
γShear strainUnitlessScalar
θVolume strainUnitlessScalar
γSurface tensionNewton per meterScalar

Symbols used to denote physical quantities related to thermal physics:
SymbolQuantity/CoefficientsS.I UnitPhysical Quantity (Scalar/Vector)
COPCoefficient of performance UnitlessScalar
wWays, number of identical microstatesUnitlessScalar
SEntropyJoule per kelvinScalar
UInternal energyJouleScalar
kThermal conductivityWatt per meter KelvinScalar
PHeat flow rateWattScalar
NNumber of particlesUnitlessScalar
nAmount of substanceMoleScalar
LLatent heat/specific latent heatJoule per kilogramScalar
cSpecific heat capacityJoule per kilogram KelvinScalar
ΒVolume expansivity, coefficient of volume thermal expansionInverse kelvinScalar
αLinear expansivity, coefficient of thermal expansionInverse kelvinScalar

Symbols used to denote physical quantities related to Waves and Optics:
SymbolQuantity/CoefficientsS.I UnitPhysical Quantity (Scalar/Vector)
fFocal lengthMeterScalar
nIndex of refractionUnitlessScalar
LLevelDecibel, decineperScalar
IIntensityWatt per square meterScalar
v, cWave speedMeter per secondScalar
PPower of a lensDioptreScalar

Symbols used to denote physical quantities related to Electricity and Magnetism:
SymbolQuantity/CoefficientsS.I UnitPhysical Quantity (Scalar/Vector)
SPoynting vector, intensityWatt per square meterFunctions as vector
ηEnergy densityJoule per cubic meterScalar
nTurns per unit lengthInverse meterScalar
NNumber of turnsUnitlessScalar
ΦBMagnetic fluxWeberVector
BMagnetic fieldTeslaFunctions as vector
FBMagnetic forceNewtonFunctions as vector
σConductivitySiemens per meterScalar
R, rElectric resistance/internal resistanceOhmScalar
IElectric currentAmpereScalar
ϵDielectric constantUnitlessscalar
Electromotive force (emf)VoltScalar
V voltage, electric potentialVoltScalar
UEElectric potential energyJouleScalar
ΦEElectric fluxNewton meter squared per coulombFunctions as vector
EElectric fieldNewton per coulomb/volt per meterFunctions as vector
FEElectrostatic forceNewtonFunctions as vector
λLinear charge densityKilogram per meterScalar
σArea charge densityKilogram per square meterScalar
ρVolume charge densityKilogram per cubic meterScalar
q, QElectric chargeCoulombScalar

Symbols used in modern physics:
SymbolQuantity/CoefficientsS.I UnitPhysical Quantity (Scalar/Vector)
DDose/ dose absorbedgrayScalar
ψ(r,t), ψ(r)φ(t)Wave functionUnitlessFunctions as vector
ΦWork functionJouleScalar
HEffective doseSievertScalar
ΓLorentz factor/Lorentz gammaUnitlessScalar