Symbol 
Meaning 
A 
area 
a 
acceleration 
B 
magnetic field 
C 
capacitance, heat capacity 
c 
speed of light (in a vacuum), speed of sound, specific
heat capacity 
D 
electric displacement 
d 
distance, diameter, differential (e.g. dx) 
E 
energy, electric field 
F 
force 
f 
friction, frequency, function 
G 
gravitational constant 
g 
acceleration due to gravity 
H 
magnetic field 
h 
height, Planck constant 

reduced Planck constant 
I 
electric current, sound intensity, moment of inertia 
i 
imaginary unit 
J 
current density 
k 
Boltzmann constant, thermal conductivity 
L 
angular momentum, inductance 
l 
length 
M 
moment of force 
m 
mass 
n 
refractive index 
P 
power, pressure 
p 
momentum 
Q 
electric charge, heat 
R 
electrical resistance 
r 
radius, radius vector (position) 
S 
surface area, entropy, action 
s 
displacement 
T 
temperature, period 
t 
time 
U 
internal energy, potential energy 
V 
volume, voltage, shear force 
v 
velocity 
W 
mechanical work 
w 
width 
x 
a generic unknown, displacement 
γ 
(Gamma) Lorentz factor, photon, gamma ray 
Δ 
(Delta) a change in a variable (e.g. Δx) 
δ 
(Delta) displacement (usually small) 
ε 
(Epsilon) strain 
ζ 
(Zeta) damping ratio 
η 
(Eta) energy efficiency 
θ 
(Theta) angle 
λ 
(Lambda) wavelength 
μ 
(Mu) coefficient of friction, dynamic viscosity, permeability (electromagnetism) 
ν 
(Nu) kinematic viscosity 
π 
(Pi) 3.14159... 
ρ 
(Rho) resistivity, density, charge density 
Σ 
(Sigma) summation operator 
σ 
(Sigma) electrical conductivity, normal stress 
τ 
(Tau) torque, shear stress, time constant 
Φ 
(Phi) magnetic flux 
φ 
(Phi) electric potential 
Ω 
(Omega) ohm 
ω 
(Omega) angular frequency 