Mu (letter)

From Wikinfo

Greek alphabet
Αα	Alpha	Νν	Nu
Ββ	Beta	Ξξ	Xi
Γγ	Gamma	Οο	Omicron
Δδ	Delta	Ππ	Pi
Εε	Epsilon	Ρρ	Rho
Ζζ	Zeta	Σσς	Sigma
Ηη	Eta	Ττ	Tau
Θθ	Theta	Υυ	Upsilon
Ιι	Iota	Φφ	Phi
Κκ	Kappa	Χχ	Chi
Λλ	Lambda	Ψψ	Psi
Μμ	Mu	Ωω	Omega
Obsolete letters
File:Digamma uc lc.svg	Digamma	File:Qoppa uc lc.svg	Qoppa
File:San uc lc.svg	San	File:Sampi uc lc.svg	Sampi
Other characters
File:Stigma uc lc.svg	Stigma	File:Sho uc lc.svg	Sho
File:Heta uc lc.svg	Heta
Greek diacritics

Mu (uppercase Μ lowercase μ), is the letter of the Greek alphabet, used to represent the "[m]" sound in Greek. In the system of Greek numerals it has a value of 40. Letters that came from it include the Roman M and Cyrillic М.

The lower-case letter μ is used as the symbol for:

• The M??s function in mathematics.
• The SI prefix micro-, which represents one millionth, or 10^-6.
• Formerly, the micron, an old unit corresponding to the micrometer.
• The coefficient of friction, ie. the ratio of the limiting frictional force between two surfaces against the normal contact force.
• The elementary particle called muon in particle physics.
• Reduced mass in the two-body problem in physics.
• Rarely, to distinguish between one item represented by m and another (but m might be an easier option).
• The permeability in physics and electrical engineering.

References

• Adapted from the Wikipedia article, "Mu_(letter)" http://en.wikipedia.org/wiki/Mu_(letter), used under the GNU Free Documentation License