Micrometre

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 an SI derived unit of length 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]

Micrometre
A 6 μm diameter carbon filament above a 50 μm diameter human hair
General information
Unit systemmetric
Unit oflength
Symbolμm
Conversions
1 μm in ...... is equal to ...
   SI units   10−6 m
   Natural units   1.8897×104 a0
   imperial/US units   3.2808×10−6 ft, 3.9370×10−5 in

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.


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