Micro-
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Micro (
Greek letter μ, mu, non-italic) is a unit prefix in the metric system denoting a factor of 10−6 (one millionth).[1] Confirmed in 1960, the prefix comes from the Greek μικρός
(mikrós), meaning "small".
It is the only SI prefix which uses a character not from the Latin alphabet. In Unicode, the symbol is represented by U+03BC μ GREEK SMALL LETTER MU or the legacy symbol U+00B5 µ MICRO SIGN. The prefix "mc" is commonly used in healthcare or when the character "μ" is not available; for example, "mcg" commonly denotes a microgram.[2] The letter "u" is sometimes used instead of "μ" when non-Latin characters are not available.
Examples
- Typical bacteria are 1 to 10 micrometer (1–10 µm) in diameter.
- Eukaryotic cells are typically 10 to 100 micrometers in diameter.[3]
| Prefix | Base 10 | Decimal | Adoption [nb 1] | |
|---|---|---|---|---|
| Name | Symbol | |||
| quetta | Q | 1030 | 1000000000000000000000000000000 | 2022[4] |
| ronna | R | 1027 | 1000000000000000000000000000 | |
| yotta | Y | 1024 | 1000000000000000000000000 | 1991 |
| zetta | Z | 1021 | 1000000000000000000000 | |
| exa | E | 1018 | 1000000000000000000 | 1975[5] |
| peta | P | 1015 | 1000000000000000 | |
| tera | T | 1012 | 1000000000000 | 1960 |
| giga | G | 109 | 1000000000 | |
| mega | M | 106 | 1000000 | 1873 |
| kilo | k | 103 | 1000 | 1795 |
| hecto | h | 102 | 100 | |
| deca | da | 101 | 10 | |
| — | — | 100 | 1 | — |
| deci | d | 10−1 | 0.1 | 1795 |
| centi | c | 10−2 | 0.01 | |
| milli | m | 10−3 | 0.001 | |
| micro | μ | 10−6 | 0.000001 | 1873 |
| nano | n | 10−9 | 0.000000001 | 1960 |
| pico | p | 10−12 | 0.000000000001 | |
| femto | f | 10−15 | 0.000000000000001 | 1964 |
| atto | a | 10−18 | 0.000000000000000001 | |
| zepto | z | 10−21 | 0.000000000000000000001 | 1991 |
| yocto | y | 10−24 | 0.000000000000000000000001 | |
| ronto | r | 10−27 | 0.000000000000000000000000001 | 2022[4] |
| quecto | q | 10−30 | 0.000000000000000000000000000001 | |
| ||||
Symbol encoding in character sets
The official symbol for the
The Unicode Consortium, the Greek letter character is preferred,[8] but implementations must recognize the micro sign as well. This distinction also occurs in some legacy code pages, notably Windows-1253
.
In circumstances in which only the
BS 6430 (since 1983) allow the prefix
(µC).
Similarly, capacitor values according to the RKM code defined in IEC 60062 (since 1952) can be written as μ to be substituted by the letter u (or even U, if lowercase letters are not available), as, for example, in um for μm, or uF for μF, or in the common abbreviation UC for microcontroller4u7 (or 4U7) instead of 4μ7 if the Greek letter μ is not available.
Other abbreviating conventions
In some
physical sciences
research, "μg" remains the sole official abbreviation.
In medical data exchange according to the Health Level 7 (HL7) standard, the μ can be replaced by u as well.[14]
See also
- Microgram
- Microscope
- Microsecond
- Microwave
- Square micrometre
- List of commonly used taxonomic affixes
References
- ISBN 92-822-2213-6, archived(PDF) from the original on 2021-06-04, retrieved 2021-12-16
- ^ a b "ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations: Abbreviations for Doses/Measurement Units". Recommendations. Institute for Safe Medication Practices (ISMP). 2021-02-05. Archived from the original on 2022-12-24. Retrieved 2022-12-24.
Error-Prone Abbreviations, Symbols, and Dose Designations: µg […] Intended Meaning: Microgram […] Misinterpretation: Mistaken as mg […] Best Practice: Use mcg […]
- ^ Biology by Campbell & Reece, tenth edition. Ch. 6 "A Tour of the Cell". p. 98.
- ^ a b "On the extension of the range of SI prefixes". 2022-11-18. Retrieved 2023-02-05.
- ^ "Metric (SI) Prefixes". NIST.
- ^ Prefixes of the International System of Units, International Bureau of Weights and Measures (page visited on 9 May 2016).
- ^ (Unicode 1.0, 1991)
- ^ Unicode Technical Report #25
- ^ ISO 2955-1974: Information processing - Representations of SI and other units for use in systems with limited character sets (1st ed.). 1974.
- ^ "Table 2". ISO 2955-1983: lnformation processing - Representations of SI and other units for use in systems with limited character sets (PDF) (2nd ed.). 1983-05-15. Retrieved 2016-12-14. [1]
- ^ DIN 66030: Darstellungen von Einheitennamen in Systemen mit beschränktem Schriftzeichenvorrat (in German) (1st ed.). 1980.
- ^ "Neue Normen für die Informationsverarbeitung". Computerwoche (in German). 1981-01-09. Archived from the original on 2016-12-14. Retrieved 2016-12-14.
- ^ ISBN 978-1455759422.
- ^ "Commonly Used UCUM Codes for Healthcare Units". HL7 Deutschland e.V. 2015-11-21. Archived from the original on 2022-10-06. Retrieved 2022-12-24.
