Greek Alphabets Used in Electrical & Electronic Engineering

Electrical Technology

Uses of 24 Greek Letters as Symbols & Characters in Electrical & Electronics Engineering

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Greek Letters & Special Character in Electrical/Electronic Engineering

There are a total 24 Greek letters which are widely used in engineering, science and mathematics applications which indicates different characteristics and measurement of specific quantities. Keep in mind that the lowercase and uppercase (small & capital) letters are used to denote different values in different science and engineering disciplines. In this post, we will show the uses of 24 Greek alphabets especially in electrical and electronic engineering.

Related Post: 800+ Electrical & Electronic Abbreviations with Full Forms. A-Z

Why are Greek Alphabets Used in Scientific, Mathematical and Engineering Disciplines?

The Greek letters as special characters and symbols are used due to the following reasons.

The main reason to use Greek characters and symbols is the continuity from the ancient Phoenicians to Greek adoption and used by philosophers ( from BC 750+). Now, we follow the same and use Greek symbols in most engineering and scientific contents and technical papers.
Latin & English alphabets are widely used like A = Current in ampere, V = Voltage in Volts, P = Power in Watts, R = resistance in Ohms etc. and X,Y,Z as variables, So we can’t use the same alphabets and letters for too many different terms in scientific & engineering fields to avoid making confusion.
It is easy to memorize (& remember) the value of different quantities and constant values by using Greek alphabets instead of using their name.

Greek Symbols & Characters in EE

Following are different Greek Alphabets (Small & Capital) used as symbolic characters in Electronic & Electrical Engineering

α = Alpha

Alpha Particles
Angles, Angular Acceleration & Control angle in rectifier
Common Base Current “I_CB” & Amplification Factor in Transistors
Positive & Negative Temperature Coefficient of Resistance
Thermal Diffusivity, Thermal Expansion & Coefficient of Heat Transfer
Attenuation Coefficient/Constant

β = Beta

High-energy & high-speed electron Beta Ray or Beta particle
Control Angle for Inverter
Feedback factor
Common-Emitter Current “I_CE“& amplification factor in Transistors,
Flux Density “B” in Magnetism & Electromagnetism
Wavelength constant
Phase constant & Phase change coefficient

γ = Gamma

Gamma Rays & Radiation
Electrical Conductivity “Υ”* (reciprocal of Resistivity “rho = ρ”)
Propagation coefficient

σ, κ & γ also used to represent the electrical conductivity.

Δ & δ = Delta

Delta Connection / Configuration “Δ” in Transformers
Loss Angles “δ”
Damping Coefficient “δ” (Decay constant)
Modulation Factor (F.M) “δ”
Decrement & Increment
Secondary-emission Ratio
Frequency Deviation Δf
Phase Deviation ΔΦ

Mostly, Delta “Δ” is used as difference or change in different quantities i.e. Δt/Δt … e.g. difference / change in flux “Φ” and Time “T” respectively.

ε = Epsilon

Electric Constant in free space “ε₀ ≈ 8.854×10⁻¹² F⋅m⁻¹)
Dielectric Current / Constant (Capacitivity or Permittivity)
Permittivity (Relative “ε_r” , Vacuum or fee space “ε₀” & (Absolute) “ε”.
Emissivity (It is a measure of an object’s ability to emit infrared energy)
Regulation
Fermi Energy
Electron Energy
Electric Field Intensity

ζ = Zeta

Damping ratio of an oscillating system or Damping Factor “ζ (zeta)”
Zeta potential, also known as “electro-kinetic potential”
Impedance “Z”

η = Eta

Hysteresis (losses in Machines)
Efficiency (in Electrical Machines)
Dielectric Susceptibility
Intrinsic Standoff Ratio in UJT (Unijunction Transistors)
Intrinsic Impedance of a Medium or Wave impedance

θ = Theta

Commonly used in trigonometry, power factor and calculation of phase angle between leading/lagging current and voltage.
Reluctance “the property of a magnetic circuit of opposing the passage of magnetic flux lines” Same like resistance in the electric circuit which opposes the flow of current in the conductor.
Transit Angle “the product of the transit time and the angular frequency of the sinusoidal component of the electric current.
Current Linkage “Θ”

Ι = Iota

If you like matrices you would know that uppercase Iota is used as the identity matrix. However, I find that that the lowercase is rarely used in engineering or maybe I’ve just never used an equation before with lowercase Iota. Let us know if you have.

Identity Matrix “I” as “Iota”
imaginary Number (The imaginary unit or unit imaginary number “ $i”*$ ) is a solution to the quadratic equation $x 2 + 1 = 0)$

*In electrical engineering and control systems engineering, the imaginary unit is normally denoted by “ $j”$ instead of “ $i”$ , because “ $i”$ is commonly used to denote electric current.

κ = Kappa

Curvature of the Universe (Small Kappa κ)
Einstein’s Constant of gravitation (lowercase Kappa κ)
Coupling Coefficient
Magnetic Susceptibility
Multiplication factor
Electrical conductivity*, the reciprocal of resistivity, rho (ρ).

*κ, σ & γ also used to represent the electrical conductivity.

λ = Lambda

Leakage coefficient or leakage factor in Magnetic Circuit “λ”.
Symbol of Wavelength
Thermal Conductivity
Logarithmic decrement
Line density of charge
Photosensitivity
Attenuation Constant
Permeance (a measure of the ease with which magnetic flux can be admitted through a material or magnetic circuit.). Λ is permeance (in WbA⁻¹).

μ = Mu

Magnetic constant in free space (μ₀ = 4π x 10^-7 H/m)
Magnetomotive force MMF (F or f_μ)
Used as the prefix ‘micro’ for measuring different quantities such as capacitance in Microfarad = 1 μF = 0.000001 F = 10⁻⁶ (One millionth of farad).
Fraction Coefficient
Mobility of Electron (µ_e)
Absolute permeability (μ)
Relative permeability (μ_r)
Microprocessor (μP)

ν = Nu

Kinematic viscosity
Reluctivity
Frequency

ξ = Xi

Potential difference “ξ” (in volts)
Pippard’s cohesion length in superconductors
Output Coefficient
Average logarithmic energy decrement per collision for Neutron calculations in nuclear physics.

ο = Omicron

The only Greek letter which doesn’t used to represent any thing in electrical & electronic engineering expect it represents the 15th Star in constellation group (Astronomical terminology).

π = Pi

Pi Reparents the well known (mathematical constant) and universally used number having the value of π = 3.14159.
Circle’s circumference and diameter i.e. circumference / diameter = Pi “π“.
Mathematical operation of Product & Multiplication “Π”.

ρ = Rho

Resistivity “ρ” (reciprocal of conductivity “Y or σ”)
Volume’s Density & Surface Density of Charge
Reflection factor & reflection coefficient

σ = Sigma

Conductivity “σ or Y*” (reciprocal of Resistivity “ρ”)
Leakage Factor in Inductance “σ”.
The Upper case sigma “Σ” represents the “Sum of” any two or more values i.e. Σ_IN = Σ_OUT e.g. Sum of incoming current = Sum of outgoing current at a point (Kirchhoff’s current law “KCL”).
The lower case sigma “” represents almost all kind of stress (not on engineering students) but thermal stress etc.
Stefan Boltzmann Constant (for Heat emitted by a black body) σ = 5.67051 × 10⁻⁸ W m⁻² K⁻⁴.

σ, κ & γ also used to represent the electrical conductivity.

τ = Tau

More stress! Tau is typically used to denote a specific type of stress called shear stress, as well as propagation constant, Thomson coefficient, the time constant, time-phase displacement, and transmission factor.

The propagation constant of a sinusoidal electromagnetic wave “τ”.
Thomson coefficient (thermal expansion coefficient and the heat capacity.)
Time-phase displacement (Phase difference & phase shift in an AC circuits)
Transmission factor
Torque in N/m
Volume resistivity
Time Constant (in capacitive & RLC etc. circuits)

Υ = Upsilon

Electrical Conductivity “Υ”* (reciprocal of Resistivity “rho = ρ”)
Ratio of Specific Heat capacities (Υ = C_P / C_V)
Ratio of Mass & Light

φ & Φ = Phi

Phase angle & Phase displacement (Most common in Power factor correction & improvement for the legging/leading phase angle between voltage and current.
Power Factor = CosΦ = kW/kVA
Magnetic flux “Φ_B” (Magnetic Lines of Force) & Radiant Flux
Electric flux “Φ_E” (Electric Lines of Force)
Flow rate of Heat “Φ_th“

χ = Chi

Electric Susceptibility “χ, χ_e, χ_ε“
Magnetic Susceptibility “χ, κ)

ψ = Psi

Magnetic Flux Linkage “ψ”.
Electric Flux
Phase difference

ω & Ω = Omega

The SI Unit of Electric Resistance (R) is “Ω = Ohm”.
The Unit of Impedance (Z) is “Ω”.
The Unit of Inductive & Capacitive Reactance’s (X_L & X_C) is “Ω”.
Angular Frequency & Velocity “ω” i.e. ω = 2πf.
Intrinsic Impedance (Z_o) in free space = 3767303 Ω

Good to Know: Inverted capital Greek letter omega ℧ (i.e. Upside-down Ω) is represents the unit of conductivity (Siemens “S” where the siemens is the derived unit of electric conductance “G”, electric susceptance, and electric admittance). ℧ is spelled backward to the Ohm i.e. “Mho”. In Short, Ω = Ohm & ℧ = Mho.

Table of Greek Alphabets Used in Electrical / Electronic Engineering

Uses of Greek Alphabets (Letters) Characters & Symbols in Electrical & Electronic Eng.
Greek Symbols		Greek Letter	Used to Denote Electrical & Electronic Quantities & Terms
Capital	Small	Greek Letter
Α	α	Alpha	Temperature Coefficient of Resistance, Angles, Amplification Factor, Attenuation Coefficient/Constant.
Β	β	Beta	Control Angle for Inverter, Feedback factor, Phase constant, Wavelength constant, Flux Density “B”.
Γ	γ	Gamma	Conductivity “Υ”, Propagation Coefficient.
Δ	δ	Delta	Delta Connection “Δ” in T/F, Loss Angles, Modulation Factor, Frequency Deviation, Phase Deviation, Damping Coefficient.
Ε	ε	Epsilon	Electric Field Intensity, Permittivity, Dielectric Current / Constant, Regulation, Emissivity, Electron Energy.
Ζ	ζ	Zeta	Impedance “Z”, Damping Ratio/Factor, Zeta potential (aka “electro-kinetic potential”).
Η	η	Eta	Hysteresis Losses, Machine’s Efficiency, Dielectric Susceptibility, Intrinsic Impedance, Intrinsic Standoff Ratio in UJT.
Θ	θ	Theta	Reluctance, Transit Angle, Current Linkage, Phase angle.
Ι	ι	Iota	Identity Matrix, Imaginary Number (i or j).
Κ	κ	Kappa	Electrical conductivity, Magnetic Susceptibility, Multiplication factor, Multiplication factor.
Λ	λ	Lambda	Permeance, Leakage coefficient/factor, Thermal Conductivity, wavelength, Line density of charge, Attenuation constant, Photosensitivity.
Μ	μ	Mu	Magnetic constant, Permeability, prefix ‘micro’ for the micro multiplier (μF=10⁻⁶), Mobility of Electron, Microprocessor, Magnetomotive force MMF.
Ν	ν	Nu	Reluctivity, Kinematic viscosity, Frequency.
Ξ	ξ	Xi	Potential difference, Pippard’s cohesion length in superconductors, Output Coefficient.
Ο	ο	Omicron	No uses in EE but represents the 15th Star in constellation group (Astronomical terminology).
Π	π	Pi	Well known constant as Pi = π = 3.14159…, Product & Multiplication “Π” in Math, Circle’s circumference and diameter.
Ρ	ρ	Rho	Resistivity “ρ”, Surface Density of Charge, Volume’s Density, Reflection factor/coefficient.
Σ	σ	Sigma	Conductivity “σ or Y, Leakage Factor in Inductance, Summation “Σ”, Stefan Boltzmann Constant (Heat of black bodies).
Τ	τ	Tau	Time Constant (RLC circuits), Transmission factor, Torque, Thomson coefficient, propagation constant.
Υ	υ	Upsilon	Electrical Conductivity “Υ”, Ratio of Specific Heat capacities, Ratio of Mass & Light.
Φ	φ	Phi	Phase angle & Phase displacement, Power Factor “CosΦ”, Magnetic flux “Φ_B“, Electric flux “Φ_E“, Flow rate of Heat “Φ_th“.
Χ	χ	Chi	Electric Susceptibility, Magnetic Susceptibility.
Ψ	ψ	Psi	Electric Flux, Magnetic Flux Linkage, Phase difference.
Ω	ω	Omega	Resistance “Ω”, Impedance, Reactances, Intrinsic Impedance, Angular Frequency/Velocity.

Here is the table of Greek letters in EE-Engineering in the image format if you need to download to have a copy with you.

Click image to enlarge

That’s it. Now it’s your turn to mention the important uses of 24 Greek alphabets (lowercase and uppercase) in the field of electrical and electronic engineering (if any other than the above mentioned) in the below comment box.