Physics Symbols

What is the Importance of Physics Symbols?

In Physics, different symbols or documentations are utilized to mean various amounts. The indications make the portrayal of the amounts simpler. In this page, probably the most well known physics symbols are referenced. Let us assume that a lady drives her car at a speed of 30 kmph and reaches her hometown in 2 hrs and if she drives at 50 kmph, she reaches in 1.5 hr. So, if we have to represent these units as symbols, how can we do that?

Symbols used for physical quantities are vastly different. Sometimes, the symbol may be the first letter of the physical quantities they represent, like ‘d’, which stands for distance. Other times, they may be completely unrelated to the name of the physical quantities, such as c symbolises the speed of light.

They may also be in the form of Greek characters, like λ, which stands for wavelength. Below is complete list of the most commonly used symbols in physics with their SI units.

Symbols for Physical Quantities Related to Space and Time

Symbols	Quantity/ Coefficients	S.I. Unit	Physical Quantity (Scalar/Vector)
r	Radius, the radius of curvature	Metre	Functions as both scalar and vector
s	Displacement	Metre	Vector
d	Distance	Metre	Scalar
θ	Angular displacement,	Radian	Vector
φ	The rotational angle	Radian	A uniquely-defined magnitude and direction, but is not a vector quantity.(Does Not obey commutative law)
x, y, z	Cartesian Coordinates	Unitless	Scalar
î, ĵ, k̂	Cartesian unit vectors	Unitless	Vector
r, θ, φ	Spherical coordinates	Metre/Radian	Vector
r̂, θ̂, φ̂	Spherical vectors	Unitless	Vector
r, θ, z	Cylindrical coordinates	Metre/Radian	Scalar
r̂, θ̂, ẑ	Cylindrical vectors	Unitless	Vector
n̂	Normal vector	Unitless	Vector
t̂	Tangential unit vector	Unitless	Vector
h	Height, Depth	Metre	Scalar
ℓ, L	Length	Metre	Scalar
t	Time	Second	Scalar
D (= 2 r)	Diameter	Metre	Scalar
C	Circumference	Metre	Scalar
A	Area	Square Metre	Functions as both scalar and vector (like Area vector in a magnetic flux formula)
V	Volume	Cubic Metre (m3)	Scalar
τ	Time Constant	Second (s)	Scalar
T	Periodic time	Second (s)	Scalar
f	Frequency	1/second or (1/s)	Scalar
ω	Angular frequency	Rad/s	Scalar

 

Physics Symbols Related to Mechanics

Symbols	Quantity/ Coefficients	S.I. Unit	Physical Quantity (Scalar/Vector)
v	Velocity, speed	metre/second (m/s)	Speed = ScalarVelocity = vector
a	Acceleration	metre/square second (m/s2)	Vector
g	Acceleration due to gravity	metre/square second	Vector
ac	Centripetal/Centrifugal acceleration	metre/square second	Vector
m	Mass	Kilogram (kg)	Scalar
F	Force	Newton (N)	Vector
W/Fg	Force due to gravity/Weight	Newton	Vector
Fg/ N	Normal force	N	Vector
Ff	Force of friction	N	Vector
µ	Coefficient of friction	Unitless	Scalar
p	Momentum	Kg.m/s	Vector
J	Impulse	N/s	Vector
E	Energy	Joule  (J)	Scalar
K	Kinetic energy	J	Scalar
U	Potential Energy	J	Scalar
Vg	Gravitational potential	J/kg	Scalar
η	Efficiency	Unitless	Scalar
P	Power	Watt	Scalar
α	Rotational acceleration	Radian per second squared (Rad/s2)	Vector
ω	Rotational velocity	Rad/s	Vector
τ	Torque	N/m	Vector
L	Angular momentum	Kilogram meter squared per second Kg.m2/s	Vector
ρ	DensityVolume Mass density	Kilogram per cubic meter	Scalar
I	Moment of inertia	Kg.m2	Scalar

Physical Symbols Related to Fluid Mechanics

Symbols	Quantity/ Coefficients	S.I. Unit	Physical Quantity (Scalar/Vector)
λ	Linear mass density	kg/m	Scalar
σ	Area mass density	Kilogram per square meter (kg/m2)	Scalar
FB, B	Buoyancy	N	Vector
qm	Mass flow rate	kg/s	Scalar
qV	Volume flow rate	m3/s	Scalar
FD, R	Drag or air resistance	N	Vector
CD	Drag Coefficient	Unitless	Scalar
η	Viscosity	Pascal-second	Scalar
v	Kinematic Viscosity	m2/s	Scalar
σ	Area mass density	kg/m2	Scalar
Re	Reynolds number	Unitless	Scalar
Fr	Froude number	Unitless	Scalar
Ma	Mach number	Unitless	Scalar

Symbols Related to Solid Mechanics

Symbols	Quantity/ Coefficients	S.I. Unit	Physical Quantity (Scalar/Vector)
P	Pressure	Pascal / N/m2	Scalar
σ	Stress	Pascal	Scalar
τ	Shear stress	Pascal	Scalar
k	Spring constant	N/m	Scalar
E	Young’s modulus of elasticity	Pascal	Scalar
G	Shear modulus of rigidity	Pascal	Scalar
ε	Linear strain	Unitless	Scalar
γ	Shear strain	Unitless	Scalar
θ	Volume strain	Unitless	Scalar
S	Surface Tension	N/m	Scalar
K	Bulk modulus of compression	Pascal	Scalar

Physical Quantities Related to Thermal Physics

Symbols	Quantity/ Coefficients	S.I. Unit	Physical Quantity (Scalar/Vector)
k	Thermal conductivity	W/m.K	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	J/kg	Scalar
c	Specific heat capacity	J/kg. K	Scalar
Q	Heat	J	Scalar
B	Volume expansivity, coefficient of volume thermal expansion	1/K (inverse Kelvin)	Scalar
α	Linear expansivity, coefficient of thermal expansion	1/K (inverse Kelvin)	Scalar
T	Temperature	Kelvin	Scalar

Physical Symbol Related to Wave and Optics

Symbol	Quantity/Coefficients	S.I Unit	Physical Quantity (Scalar/Vector)
M	Magnification	Untiless	Scalar
f	Focal length	Metre	Scalar
n	Index of refraction	Unitless	Scalar
L	Level	Decibel (dB), decineper	Scalar
I	Intensity	W/m2	Scalar
v, c	Wave speed	m/s	Scalar
λ	Wavelength	Metre (m)	Scalar
P	Power of a lens	Dioptre (D)	Scalar

Physics Symbols Related to Electricity and Magnetism

Symbol	Quantity/Coefficients	S.I Unit	Physical Quantity (Scalar/Vector)
S	Poynting vector, intensity	W/m2	Vector
η	Energy density	J/m3	Scalar
n	Turns per unit length	1/m	Scalar
N	Number of turns	Unitless	Scalar
φB	Magnetic flux	Weber	Vector
B	Magnetic field	Tesla	Vector
FB	Magnetic force	N	Vector
σ	Conductivity	Siemens/m (S/m)	Scalar
G	Conductance	Siemens	Scalar
ρ	Resistivity	Ohm-m	Scalar
R, r	Electric resistance/internal resistance	Ohm	Scalar
I	Electric current	Ampere (A)	Scalar
ϵ	Dielectric constant	Unitless	Scalar
ℰ	Electromotive Force	Volt (V)	Scalar
C	Capacitance	Farad (F)	Scalar
V	Voltage, electric potential	V	Scalar
UE	Electric potential energy	J	Scalar
φE	Electric flux	Newton meter squared per coulomb (N/m2.C)	Vector
E	Electric field	N/C or V/m	Vector
FE	Electrostatic force	N	Vector
λ	Linear charge density	kg/m	Scalar
σ	Area charge density	kg/m2	Scalar
ρ	Volume charge density	kg/m3	Scalar
q, Q	Electric charge	Coulomb (C)	Scalar

Symbols Used in Modern Physics

Symbol	Quantity/Coefficients	S.I Unit	Physical Quantity (Scalar/Vector)
D	Dose/ dose absorbed	Gray (Gy)	Scalar
t1⁄2	Half-life	Second	Vector
ψ(r,t), ψ(r)φ(t)	Wave function	Unitless	Scalar
W	Work function	J	Scalar
H	Effective Dose	Sievert	Scalar
Γ	Lorentz factor/Lorentz gamma	Unitless	Scalar

From the above text on physics symbols, we comprehend that in Physics, we utilize different symbols or notations to signify various amounts. The meanings make the portrayal of the amounts more straightforward. It was also interesting to see that some physics symbols were very relatable (like “d” for distance) while some were unrelatable (like “c” for the speed of light or “λ” for wavelength). Also, we noticed that a particular symbol was related to more than one quantity.