The Online Encyclopedia and Dictionary







A micrometre (American spelling: micrometer), symbol m, is an SI unit of length. It is defined as one millionth of a metre (1×10−6 m), equivalent to one thousandth of a millimetre.

The symbol (Unicode character U+00B5; HTML µ) is the "micro sign"; it is derived from the Greek letter mu (μ); the two may or may not look the same, depending on the font. The symbol "um" is sometimes used, when the and μ are not available, e.g. when using a typewriter. The micrometre is a common unit of measurement for wavelengths of infrared radiation.

Some people (especially in astronomy and the semiconductor business) use the old name micron and/or the solitary symbol for the same thing, even though it is officially discouraged. They were official from 1879-1967.

nanometre << micrometre << millimetre

See also

External link

  • Conversion of length and distance units

Last updated: 02-08-2005 16:17:35
Last updated: 05-03-2005 17:50:55