Practical Electronics/Greek Alphabet

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.