Mu (letter)

Mu (Μ μ) is the 12th letter of the Greek alphabet and has a numeric value of 40.

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

• The SI prefix micro-, which represents one millionth, or 10^-6.
• Formerly, the micron, an old unit corresponding to the micrometer.
• Rarely, to distinguish between one item represented by m and another (but m might be an easier option).
• The coefficient of friction, ie. the ratio of the limiting frictional force between two surfaces against the normal contact force.

See also:

• Alpha - Beta - Gamma - Delta - Epsilon - Digamma - Zeta - Eta - Theta - Iota - Kappa - Lambda - Mu - Nu - Xi - Omicron - Pi - San - Qoppa - Rho - Sigma - Tau - Upsilon - Phi - Chi - Psi - Omega - Sampi