Comprehensive Guide to Physics Symbols

This guide provides an overview of important symbols used throughout various branches of physics, including their pronunciations and general usage.

Whenever you encounter a new symbol in your physics studies, refer to this guide for a quick explanation and pronunciation.

Greek Letters

Symbol	Name	Pronunciation	Common Uses
α	Alpha	AL-fuh	Angular acceleration, alpha particle, fine-structure constant
β	Beta	BAY-tuh	Beta particle, velocity relative to speed of light
γ	Gamma	GAM-uh	Lorentz factor, photon
Δ	Delta	DEL-tuh	Change in a quantity
ε	Epsilon	EP-suh-lon	Permittivity, small quantity
ζ	Zeta	ZAY-tuh	Damping factor
η	Eta	AY-tuh	Efficiency
θ	Theta	THAY-tuh	Angle
ι	Iota	eye-OH-tuh	Rarely used
κ	Kappa	KAP-uh	Thermal conductivity
λ	Lambda	LAM-duh	Wavelength
μ	Mu	MYOO	Coefficient of friction, permeability
ν	Nu	NOO	Frequency
ξ	Xi	KSEE or ZYE	Displacement
π	Pi	PIE	Ratio of circumference to diameter (3.14159...)
ρ	Rho	ROH	Density
σ	Sigma	SIG-muh	Stress, standard deviation
τ	Tau	TAU (rhymes with "now")	Torque, time constant
υ	Upsilon	UP-suh-lon	Rarely used
φ	Phi	FEE or FYE	Electric potential, angle
χ	Chi	KYE	Magnetic susceptibility
ψ	Psi	SIGH or PSEE	Wave function
ω	Omega	oh-MAY-guh	Angular velocity

Latin and Other Symbols

Symbol	Pronunciation	Common Uses
a	ay	Acceleration
A	ay	Area
B	bee	Magnetic field
c	see	Speed of light
C	see	Capacitance
d	dee	Derivative, distance
e	ee	Elementary charge
E	ee	Electric field, energy
f	eff	Frequency, function
F	eff	Force
g	jee	Gravitational acceleration
G	jee	Gravitational constant
h	aych	Planck's constant
H	aych	Magnetic field strength
I	eye	Current
J	jay	Current density
k	kay	Spring constant, Boltzmann constant
K	kay	Kinetic energy
L	el	Angular momentum, inductance
m	em	Mass
M	em	Molar mass
n	en	Number
N	en	Number of turns (in a coil)
p	pee	Momentum
P	pee	Power
q	kyoo	Charge
Q	kyoo	Heat
r	ar	Radius, position vector
R	ar	Resistance
s	ess	Displacement
S	ess	Entropy
t	tee	Time
T	tee	Temperature, period
U	yoo	Potential energy
v	vee	Velocity
V	vee	Volume, voltage
W	double-yoo	Work
x, y, z	eks, why, zee	Cartesian coordinates
Z	zee	Atomic number

Special Symbols and Operators

Symbol	Pronunciation	Meaning
∇	del	Gradient operator
∂	partial	Partial derivative
∑	sum	Summation
∫	integral	Integration
∞	infinity	Infinity
∝	proportional to	Proportional to
≈	approximately equal to	Approximately equal to
×	cross	Vector cross product
·	dot	Vector dot product
^	hat	Unit vector

Types of Notation

1. Scalar Notation

• Scalars are typically represented by italicized letters: m (mass), T (temperature)
• Scalar quantities have magnitude but no direction

2. Vector Notation

• Vectors are often represented in several ways: a. Bold letters: F, v b. Letters with arrows above: F→, v→ c. Letters with a hat (unit vectors): î, ĵ, k̂
• Vector components are often written with subscripts: Fx, vy, az
• The magnitude of a vector is often represented by the same letter without bold or arrow: |F| or F

3. Tensor Notation

• Tensors are often represented by bold capital letters or letters with two arrows: T or T↔
• Components of tensors are often written with two subscripts: Tij

4. Matrix Notation

• Matrices are often represented by bold capital letters or square brackets: A or [A]
• Elements of matrices are often written with two subscripts: Aij

5. Bra-Ket Notation (Dirac Notation)

• Used in quantum mechanics
• Bra: ⟨ψ|
• Ket: |ψ⟩
• Inner product: ⟨ψ|φ⟩

6. Einstein Summation Notation

• Repeated indices in a term imply summation over that index
• Example: AiBi = A1B1 + A2B2 + A3B3

Common Uses for Subscripts and Superscripts

Subscripts

1. Component indication:

   • Fx, Fy, Fz: x, y, and z components of force

2. Particle or object identification:

   • m1, m2: masses of object 1 and object 2

3. Initial and final states:

   • vi: initial velocity
   • vf: final velocity

4. Specific types or conditions:

   • Ek: kinetic energy
   • Ep: potential energy

5. Maximum or minimum values:

   • vmax: maximum velocity
   • Imin: minimum moment of inertia

6. Partial derivatives:

   • ∂x/∂t: partial derivative of x with respect to t

Superscripts

1. Powers:

   • v²: velocity squared
   • r³: radius cubed

2. Atomic or nuclear states:

   • ²³⁵U: uranium-235 isotope

3. Charge:

   • e⁻: electron
   • p⁺: proton

4. Vector components in specific coordinate systems:

   • vʳ, vᶿ, vᵠ: radial, polar, and azimuthal components in spherical coordinates

5. Quantum numbers:

   • nˡ: principal quantum number n, azimuthal quantum number l

6. Mathematical operations:

   • A⁻¹: inverse of matrix A
   • x*: complex conjugate of x

7. Units:

   • 5.2 × 10⁶ m: 5.2 million meters

Combining Notation

Physics often combines various notation types. For example:

• ⟨ψ|Ĥ|ψ⟩: expectation value of the Hamiltonian operator in quantum mechanics
• ∇ × B = μ₀J + μ₀ε₀∂E/∂t: one of Maxwell's equations in electromagnetism

Usage Tips

1. Subscripts and superscripts are often used to provide additional information. For example, v₀ (v-nought) typically represents initial velocity.

2. In equations, variables are usually italicized, while units and mathematical constants (e.g., e for the base of natural logarithms) are not.

3. Vector quantities are often represented with bold letters or with an arrow above the symbol (e.g., **F ** or F→ for force).

4. The choice of symbol can vary between texts and fields of study. Always check the definitions provided in your specific context.

5. Some symbols have different meanings in different branches of physics. For example, σ can represent stress in mechanics or Stefan-Boltzmann constant in thermodynamics.

6. In quantum mechanics, the hat symbol (^) is often used to denote operators.

7. Primes (′) are often used to denote related quantities or derivatives with respect to a variable other than time.

Remember, while this guide covers many common symbols, it's not exhaustive. Physics is a vast field, and symbols may vary depending on the specific area of study or the preferences of individual authors or institutions.