# 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:
 Symbol Quantity/ Coefficients S.I Unit Physical Quantity (Scalar/Vector) r Radius, the radius of curvature Meter Functions as both scalar and vector s Displacement Meter Vector d Distance Radian Scalar θ, φ Angular displacement, angular separation, the rotational angle Meter Functions as both scalar and vector x, y, z Cartesian coordinates Unitless Scalar î, ĵ, k̂ Cartesian unit vectors Unitless Vector r, θ, φ Spherical coordinates Meter/Radian Scalar r̂, θ̂, φ̂ Spherical unit vectors Unitless Vector r, θ, z Cylindrical coordinates Meter/Radian Scalar r̂, θ̂, ẑ Cylindrical unit vectors Unitless Vector n̂ Normal unit vector Unitless Vector t̂ Tangential unit vector Unitless Vector h Height, depth Meter Scalar ℓ, L Length Meter Scalar t Time Second Scalar D Diameter Meter Scalar C Circumference Meter Scalar A, A Area Square meter Functions as both scalar and vector V Volume Cubic meter Scalar t Time, duration Second Scalar T Periodic time Second Scalar τ Time Constant Second Scalar f Frequency Hertz Scalar ω Angular frequency Radian per second Scalar

Symbols used to denote physical quantities related to Mechanics:
 Symbol Quantity/ Coefficients S.I Unit Physical Quantity (Scalar/Vector) v Velocity, speed meter per second Functions as vector a Acceleration meter per second squared Functions as and vector ac Centripetal/Centrifugal acceleration meter per second squared Functions as vector g Acceleration due to gravity meter per second squared Functions vector m Mass Kilogram Scalar F Force Newton Functions as vector Fg /W Force due to gravity/Weight Newton Functions as vector Fn, N Normal force, normal Newton Functions as vector Ff Force of friction Newton Functions as vector µ Coefficient of friction Unitless Scalar p Momentum Kilogram meter per second Functions as vector J Impulse Newton second Functions as vector E Energy Joule Scalar K Kinetic energy Joule Scalar U Potential energy Joule Scalar Vg Gravitational potential Joule per kilogram Scalar η Efficiency Unitless Scalar P Power Watt Scalar ω Rotational speed, rotational velocity Radian per second Functions as vector α Rotational acceleration Radian per second squared Functions as vector τ Torque Newton meter Functions as vector I Moment of inertia Kilogram meter squared Scalar L Angular momentum Kilogram meter squared per second Functions as vector H Angular impulse Newton meter second Functions as vector k Spring constant Newton per meter Scalar p Pressure Pascal Scalar σ Stress Pascal Scalar τ Shear stress Pascal Scalar ρ Density, volume mass density Kilogram per cubic meter Scalar σ Area mass density Kilogram per square meter Scalar λ Linear mass density Kilogram per meter Scalar FB, B Buoyancy Newton Functions as vector qm Mass flow rate Kilogram per second Scalar qV Volume flow rate Cubic meter per second Scalar FD, R Drag or air resistance Newton Functions as vector CD Drag coefficient Unitless Scalar η Viscosi Pascal-second Scalar ν Kinematic viscosity Square meter per second Scalar Ma Mach number Unitless Scalar Re Reynolds number Unitless Scalar Fr Froude number Unitless Scalar E Young’s modulus of elasticity Pascal Scalar G Shear modulus of rigidity Pascal Scalar K Bulk modulus of compression Pascal Scalar ε Linear strain Unitless Scalar γ Shear strain Unitless Scalar θ Volume strain Unitless Scalar γ Surface tension Newton per meter Scalar

Symbols used to denote physical quantities related to thermal physics:
 Symbol Quantity/Coefficients S.I Unit Physical Quantity (Scalar/Vector) COP Coefficient of performance Unitless Scalar w Ways, number of identical microstates Unitless Scalar S Entropy Joule per kelvin Scalar U Internal energy Joule Scalar ε Emissivity Unitless Scalar k Thermal conductivity Watt per meter Kelvin Scalar P Heat flow rate Watt Scalar N Number of particles Unitless Scalar n Amount of substance Mole Scalar L Latent heat/specific latent heat Joule per kilogram Scalar c Specific heat capacity Joule per kilogram Kelvin Scalar Q Heat Joule Scalar Β Volume expansivity, coefficient of volume thermal expansion Inverse kelvin Scalar α Linear expansivity, coefficient of thermal expansion Inverse kelvin Scalar T Temperature Kelvin Scalar

Symbols used to denote physical quantities related to Waves and Optics:
 Symbol Quantity/Coefficients S.I Unit Physical Quantity (Scalar/Vector) M Magnification Unitless Scalar f Focal length Meter Scalar n Index of refraction Unitless Scalar L Level Decibel, decineper Scalar I Intensity Watt per square meter Scalar v, c Wave speed Meter per second Scalar λ Wavelength Meter Scalar P Power of a lens Dioptre Scalar

Symbols used to denote physical quantities related to Electricity and Magnetism:
 Symbol Quantity/Coefficients S.I Unit Physical Quantity (Scalar/Vector) S Poynting vector, intensity Watt per square meter Functions as vector η Energy density Joule per cubic meter Scalar n Turns per unit length Inverse meter Scalar N Number of turns Unitless Scalar ΦB Magnetic flux Weber Vector B Magnetic field Tesla Functions as vector FB Magnetic force Newton Functions as vector σ Conductivity Siemens per meter Scalar G Conductance Siemens Scalar ρ Resistivity Ohm-meter Scalar R, r Electric resistance/internal resistance Ohm Scalar I Electric current Ampere Scalar ϵ Dielectric constant Unitless scalar C Capacitance Farad Scalar ℰ Electromotive force (emf) Volt Scalar V voltage, electric potential Volt Scalar UE Electric potential energy Joule Scalar ΦE Electric flux Newton meter squared per coulomb Functions as vector E Electric field Newton per coulomb/volt per meter Functions as vector FE Electrostatic force Newton Functions as vector λ Linear charge density Kilogram per meter Scalar σ Area charge density Kilogram per square meter Scalar ρ Volume charge density Kilogram per cubic meter Scalar q, Q Electric charge Coulomb Scalar

Symbols used in modern physics:
 Symbol Quantity/Coefficients S.I Unit Physical Quantity (Scalar/Vector) D Dose/ dose absorbed gray Scalar Half-life Second Scalar ψ(r,t), ψ(r)φ(t) Wave function Unitless Functions as vector Φ Work function Joule Scalar H Effective dose Sievert Scalar Γ Lorentz factor/Lorentz gamma Unitless Scalar