List of Physics Symbols and Names – Structured & Easy To Understand

In Physics, we use numerous symbols or notations to denote various quantities. These denotations make the representation and understanding of the quantities much easier.

In this article, we will touch upon the majority of the most popular physics symbols.

Nature of Physics Symbols

It’s interesting to note that a few physics symbols are pretty common and confusing (such as  “d” for distance), while a few are unrelatable (such as “c” for the speed of light). Now, that may generate confusion!

Below is a well-elaborated list of the most commonly used physics symbols with their SI units. Not that a specific symbol might relate to multiple quantities as well.

Symbols for physical quantities and their international units: 

Space & Time

Symbol Quantity SI unit
s, s displacement, distance meter
r, r position, separation, radius, the radius of curvature meter
x, y, z cartesian coordinates meter
θ, φ, θ, φ angle, angular displacement, angular separation, rotation angle radian
r, θ, φ spherical coordinates meter, radian
î, ĵ, k̂ cartesian unit vectors unitless
ρ, φ, z cylindrical coordinates meter, radian
r̂, θ̂, φ̂ spherical unit vectors unitless
normal unit vector unitless
ρ̂, φ̂, ẑ cylindrical unit vectors unitless
h height, depth meter
tangential unit vector unitless
d distance, separation, thickness meter
ℓ, L length meter
D diameter meter
t thickness meter
A, A area, cross-sectional area, projected area, surface area square meter
C circumference meter
t time, duration second
V volume cubic meter
τ time constant second
T period, periodic time second
ω angular frequency radian per second
f frequency hertz


Symbol Quantity SI unit Symbol
a, a acceleration meter per second squared m/s2
v, v velocity, speed meter per second m/s
g, g gravitational field, acceleration due to gravity meter per second squared m/s2
ac, ac centripetal acceleration, centrifugal acceleration meter per second squared m/s2
F, F force newton N
m mass kilogram kg
Fn, N, N normal force, normal newton N
Fg, W, W force of gravity, weight newton N
μs, μk coefficient of friction (static, kinetic) unitless
Ff, fs, fk force of friction (static, kinetic) newton N
J, J impulse newton second Ns
p, p momentum kilogram meter per second kg m/s
E energy, total energy joule J
W work joule J
U, Ug, Us potential energy (gravitational, spring) joule J
K, Kt, Kr kinetic energy (translational, rotational) joule J
η efficiency unitless
Vg gravitational potential joule per kilogram J/kg
ω, ω rotational velocity, rotational speed radian per second rad/s
P power watt W
τ, τ torque newton meter N m
α, α rotational acceleration radian per second squared rad/s2
L, L angular momentum kilogram meter squared per second kg m2/s
I moment of inertia kilogram meter squared kg m2
k spring constant newton per meter N/m
H, H angular impulse newton meter second N m s
σ normal stress pascal Pa
P pressure pascal Pa
ρ density, volume mass density kilogram per cubic meter kg/m3
τ shear stress pascal Pa
λ linear mass density kilogram per meter kg/m
σ area mass density, superficial mass density kilogram per square meter kg/m2
qm mass flow rate kilogram per second kg/s
FB, B, B buoyancy, buoyant force newton N
FD, R, R drag, aerodynamic drag, air resistance newton N
qV volume flow rate cubic meter per second m3/s
η viscosity, dynamic viscosity pascal second Pa s
C, CD drag coefficient, coefficient of drag unitless
Ma mach number unitless
ν kinematic viscosity square meter per second m2/s
Fr Froude number unitless
Re Reynolds number unitless
G shear modulus, modulus of rigidity pascal Pa
E young’s modulus, modulus of elasticity pascal Pa
ε linear strain unitless
K bulk modulus, modulus of compression pascal Pa
θ volume strain unitless
γ shear strain unitless
γ surface tension newton per meter N/m

Thermal Physics

Symbol Quantity SI unit Symbol
α linear expansivity, coefficient of linear thermal expansion inverse kelvin K−1
T temperature kelvin K
Q heat joule J
β volume expansivity, coefficient of volume thermal expansion inverse kelvin K−1
L latent heat, specific latent heat joule per kilogram J/kg
c specific heat, specific heat capacity joule per kilogram kelvin J/kg K
N number of particles unitless
n amount of substance mole
k thermal conductivity watt per meter kelvin W/m K
P heat flow rate watt W
U internal energy joule J
ε emissivity unitless
w ways, number of identical microstates unitless
S entropy joule per kelvin J/K
COP coefficient of performance unitless

Waves & Optics

Symbol Quantity SI unit Symbol
v, c wave speed meter per second m/s
λ wavelength meter m
L level decibel, decineper dB, dNp
I intensity watt per square meter W/m2
f focal length meter m
n index of refraction, absolute index of refraction unitless
M magnification unitless

Electricity & Magnetism

Symbol Quantity SI unit Symbol
ρ charge density, volume charge density coulomb per cubic meter C/m3
q, Q charge, electric charge coulomb C
λ linear charge density coulomb per meter C/m
σ area charge density, superficial charge density coulomb per square meter C/m2
E, E electric field newton per coulomb, volt per meter N/C, V/m
FE, FE electric force, electrostatic force newton N
U, UE potential energy, electric potential energy joule J
ΦE electric flux newton meter squared/coulomb, volt meter N m2/C, V m
electromotive force, emf volt V
V, VE voltage, potential, electric potential volt V
κ dielectric constant unitless
C capacitance farad F
R, r resistance, electrical resistance, internal resistance ohm Ω
I current, electric current ampère A
G conductance siemens S
ρ resistivity ohm meter Ω m
FB, FB magnetic force newton N
σ conductivity Siemens per meter S/m
ΦB magnetic flux weber Wb
B, B magnetic field tesla T
n turns per unit length turns density inverse meter m−1
N number of turns unitless
η energy density joule per cubic meter J/m3


Yes, they are a lot and truly a lot. They truly never seem to end, but when you try to learn the first twenty, you’d certainly feel that these aren’t that tough. So, do one thing – go slow and steady! Practice and remember these signs and symbols since they are going to help you in numerous exams.


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