Practical Electronics/Greek Alphabet

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Greek letters are often used in electronics, either for prefixes or to represent values, often if the normal letters run out.

Letter Name Uses
Capital Lowercase
Α α Alpha
Β β Beta
Γ γ Gamma
Δ δ Delta
Ε ε Epsilon
Ζ ζ Zeta
Η η Eta
Θ θ Theta Generally used to denote angles or phase relationships
Ι ι Iota
Κ κ Kappa
Λ λ Lambda Usually used for wavelength, but can also be used to denote an arbitrary constant.
Μ μ Mu Lowercase stands for "micro-", the prefix denoting one millionth. Can also be used to denote an arbitrary constant, usually when λ has been used already.
Ν ν Nu
Ξ ξ Xi
Ο ο Omicron
Π π Pi Lowercase denotes a mathematical constant, 3.14...
Ρ ρ Rho Lowercase can mean resistivity (not resistance) or density.
Σ σ Sigma Capital denotes the sum of a series of values.
Τ τ Tau PI multiplied by two (6.2831...)
Υ υ Upsilon
Φ φ Phi Sometimes used for angles or phase relationships, if theta has already been used. Can also represent the Golden Ratio.
Χ χ Chi
Ψ ψ Psi
Ω ω Omega Capital denotes "ohms", the unit of resistance. Lowercase can mean the "angular speed" or the rate of change of phase of a signal.