Micrometre

Last updated

micrometre
Cfaser haarrp.jpg
A 6 μm diameter carbon filament above a 50 μm diameter human hair
General information
Unit system SI
Unit of length
Symbolμm
Conversions
1 μm in ...... is equal to ...
    SI base units    10−6  m
    Natural units    1.8897×104  a0
    imperial/US  units   3.9370×10−5  in

The micrometre (international spelling as used by the International Bureau of Weights and Measures; [1] SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Units (SI) equalling 1×10−6  metre (SI standard prefix "micro-" = 10−6); that is, one millionth of a metre (or one thousandth of a millimetre, 0.001 mm, or about 0.00004  inch ). [1]

Contents

The nearest smaller common SI unit is the nanometre, equivalent to one one-thousandth of a micrometre, or one billionth of a metre (0.000000001 m).

The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, [1] and for grading wool by the diameter of the fibres. [2] The width of a single human hair ranges from approximately 20 to 200 μm. The longest human chromosome, chromosome 1, is approximately 10 μm in length.

Examples

How big is 1 micrometre? How big is 1 micrometer%3F (10690468113).jpg
How big is 1 micrometre?

Between 1 μm and 10 μm:

Between 10 μm and 100 μm:

SI standardization

The term micron and the symbol μ were officially accepted for use in isolation to denote the micrometre in 1879, but officially revoked by the International System of Units (SI) in 1967. [7] This became necessary because the older usage was incompatible with the official adoption of the unit prefix micro-, denoted μ, during the creation of the SI in 1960.

In the SI, the systematic name micrometre became the official name of the unit, and μm became the official unit symbol.

Additionally, in American English, the use of "micron" helps differentiate the unit from the micrometer, a measuring device, because the unit's name in mainstream American spelling is a homograph of the device's name. In spoken English, they may be distinguished by pronunciation, as the name of the measuring device is often stressed on the second syllable ( /mˈkrɒmɪtər/ my-KROM-it-ər), whereas the systematic pronunciation of the unit name, in accordance with the convention for pronouncing SI units in English, places the stress on the first syllable ( /ˈmkrˌmtər/ MY-kroh-meet-ər).

The plural of micron is normally microns, though micra was occasionally used before 1950. [8] [9] [10]

Symbol

The official symbol for the SI prefix micro- is a Greek lowercase mu. [11] In Unicode, there is also a micro sign with the code point U+00B5 (µ), distinct from the code point U+03BC (μ) of the Greek letter lowercase mu. According to the Unicode Consortium, the Greek letter character is preferred, [12] but implementations must recognize the micro sign as well. Most fonts use the same glyph for the two characters.

See also

Notes and references

  1. 1 2 3 "micrometre". Encyclopædia Britannica Online . Retrieved 18 May 2014.
  2. "Wool Fibre". NSW Department of Education and Communities. Archived from the original (Word Document download) on 17 June 2016. Retrieved 18 May 2014.
  3. Ramel, Gordon. "Spider Silk". Archived from the original on 4 December 2008. Retrieved 14 December 2008. A typical strand of garden spider silk has a diameter of about 0.003 mm ... Dragline silk (about .00032 inch (.008 mm) in Nephila)
  4. Smith, D.J.; Gaffney, E.A.; Blake, J.R.; Kirkman-Brown, J.C. (25 February 2009). "Human sperm accumulation near surfaces: a simulation study" (PDF). Journal of Fluid Mechanics . Cambridge University Press. 621: 295. Bibcode:2009JFM...621..289S. doi:10.1017/S0022112008004953. S2CID   3942426. Archived from the original (PDF) on 6 November 2013.
  5. "Fibreshape applications". IST - Innovative Sintering Technologies Ltd. Retrieved 4 December 2008. Histogram of Fiber Thickness [micrometre]
  6. The diameter of human hair ranges from 17 to 181 μm. Ley, Brian (1999). Elert, Glenn (ed.). "Diameter of a human hair". The Physics Factbook. Retrieved 8 December 2018.
  7. BIPM - Resolution 7 of the 13th CGPM 1967/68), "Abrogation of earlier decisions (micron, new candle.)"
  8. Proceedings of the Royal Society of Queensland. Part I. Vol. XIX. H. Pole & Co. 1907 via Google Books.
  9. Bigalow, Edward Fuller; Agassiz Association (1905). The Observer. Vol. 7–8 via Google Books.
  10. 10 micra/10 microns (Start at 1885; before that, the word "micron", singular or plural, was rare)
  11. "Prefixes of the International System of Units". International Bureau of Weights and Measures. Archived from the original on 23 May 2018. Retrieved 9 May 2016.
  12. Beeton, Barbara; Freytag, Asmus; Sargent, Murray III (30 May 2017). "Unicode Technical Report #25". Unicode Technical Reports. Unicode Consortium. p. 11.

Related Research Articles

<span class="mw-page-title-main">Centimetre</span> Unit of length

A centimetre or centimeter is a unit of length in the International System of Units (SI), equal to one hundredth of a metre, centi being the SI prefix for a factor of 1/100. The centimetre was the base unit of length in the now deprecated centimetre–gram–second (CGS) system of units.

<span class="mw-page-title-main">Diameter</span> Straight line segment that passes through the center of a circle

In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere.

<span class="mw-page-title-main">Litre</span> Unit of volume

The litre or liter is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). A cubic decimetre occupies a volume of 10 cm × 10 cm × 10 cm and is thus equal to one-thousandth of a cubic metre.

A micron is a non-SI name for micrometre (μm).

<span class="mw-page-title-main">Nanometre</span> Unit of length

The nanometre or nanometer is a unit of length in the International System of Units (SI), equal to one billionth of a metre and to 1000 picometres. One nanometre can be expressed in scientific notation as 1×10−9 m, and as 1/1000000000 metres.

A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The prefix kilo-, for example, may be added to gram to indicate multiplication by one thousand: one kilogram is equal to one thousand grams. The prefix milli-, likewise, may be added to metre to indicate division by one thousand; one millimetre is equal to one thousandth of a metre.

<span class="mw-page-title-main">Picometre</span> Unit of length (10^-12 meters)

The picometre or picometer is a unit of length in the International System of Units (SI), equal to 1×10−12 m, or one trillionth (1/1000000000000) of a metre, which is the SI base unit of length.

<span class="mw-page-title-main">Millimetre</span> Unit of length 1/1000 of a metre

The millimetre or millimeter is a unit of length in the International System of Units (SI), equal to one thousandth of a metre, which is the SI base unit of length. Therefore, there are one thousand millimetres in a metre. There are ten millimetres in a centimetre.

<span class="mw-page-title-main">Square metre</span> SI-derived unit of area

The square metre or square meter is the unit of area in the International System of Units (SI) with symbol m2. It is the area of a square with sides one metre in length.

<span class="mw-page-title-main">Mu (letter)</span> Letter in the Greek alphabet

Mu is the 12th letter of the Greek alphabet, representing the voiced bilabial nasal IPA: [m]. In the system of Greek numerals it has a value of 40. Mu was derived from the Egyptian hieroglyphic symbol for water, which had been simplified by the Phoenicians and named after their word for water, to become 𐤌 (mem). Letters that derive from mu include the Roman M and the Cyrillic М.

Micro is a unit prefix in the metric system denoting a factor of 10−6. Confirmed in 1960, the prefix comes from the Greek μικρός, meaning "small".

<span class="mw-page-title-main">Orders of magnitude (length)</span> Range of lengths from the subatomic to the astronomical scales

The following are examples of orders of magnitude for different lengths.

In the metric system, a microgram or microgramme is a unit of mass equal to one millionth of a gram. The unit symbol is μg according to the International System of Units; the recommended symbol in the United States and United Kingdom when communicating medical information is mcg. In μg the prefix symbol for micro- is the Greek letter μ (mu).

A thousandth of an inch is a derived unit of length in a system of units using inches. Equal to 11000 of an inch, a thousandth is commonly called a thou or particularly in North America a mil.

<span class="mw-page-title-main">Wool measurement</span>

A micron (micrometre) is the measurement used to express the diameter of wool fibre. Fine wool fibers have a low micron value. Fibre diameter is the most important characteristic of wool in determining its value.

<span class="mw-page-title-main">Animal fiber</span> Natural fiber from animals like silk worms and sheep

Animal fibers are natural fibers that consist largely of certain proteins. Examples include silk, hair/fur and feathers. The animal fibers used most commonly both in the manufacturing world as well as by the hand spinners are wool from domestic sheep and silk. Also very popular are alpaca fiber and mohair from Angora goats. Unusual fibers such as Angora wool from rabbits and Chiengora from dogs also exist, but are rarely used for mass production.

<span class="mw-page-title-main">Units of textile measurement</span> Systems for measuring textiles

Textile fibers, threads, yarns and fabrics are measured in a multiplicity of units.

An S number on the label of wool suits or other tailored apparel, wool fabric, or yarn, indicates the fineness of the wool fiber used in the making of the apparel, as measured by its maximum diameter in micrometres. Fiber fineness is one of the factors determining the quality and performance of a wool product. In recent years it has also become an important marketing device used by many mills, garment makers, and retailers. The S number appears as a plural with an s or 's following the number, such as 100s or 100's.

<span class="mw-page-title-main">Cubic metre</span> SI derived unit of volume

The cubic metre or cubic meter is the unit of volume in the International System of Units (SI). Its symbol is m3. It is the volume of a cube with edges one metre in length. An alternative name, which allowed a different usage with metric prefixes, was the stère, still sometimes used for dry measure. Another alternative name, no longer widely used, was the kilolitre.