# Greek Alphabets Used in Electrical & Electronic Engineering

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

Table of Contents

### 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.

### 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.

**Related Post: Electrical and Electronic Engineering Symbols**

### 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 Δ
*f* - 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 “ε
_{0}≈ 8.854×10^{−12}F⋅m^{−1}) - Dielectric Current / Constant (Capacitivity or Permittivity)
- Permittivity (Relative “ε
_{r}” , Vacuum or fee space “ε_{0}” & (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”

**Related Post: 5000+ Electrical and Electronics Engineering Formulas and Equations**

**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 (μ
_{0}= 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 | ||

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.

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