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The femtometre (American spelling femtometer) symbol fm derived from the
Danish_and_Norwegian_language">Norwegian_word__'fifteen',__grc">μέτρον">metrοn">lit=unit_of_measurement)_is__a_unit_of_length_in_the_International_System_of_Units_(SI)_equal_to_10
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−15 metres, which means a quadrillionth of one metre. This distance is sometimes called a fermi and was so named in honour of Italian Americans">Italian-American physicist
Enrico Fermi
Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" an ...
, as it is a typical length-scale of nuclear physics.
Definition and equivalents
1000000 zeptometres = 1 femtometre = 1 fermi = 0.000001
nanometre
330px, Different lengths as in respect to the molecular scale.
The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re ...
=
femtometres = 1
millimetre
330px, Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The microwave is between 1 meter to 1 millimeter.
The millimetre (American and British English spelling differences#-re, -er, ...
.
For example, the
charge radius
The rms charge radius is a measure of the size of an atomic nucleus, particularly the proton distribution. It can be measured by the scattering of electrons by the nucleus. Relative changes in the mean squared nuclear charge distribution can b ...
of a
proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
is approximately 0.841 femtometres while
the radius of a
gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
nucleus
Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to:
* Atomic nucleus, the very dense central region of an atom
*Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA
Nucl ...
is approximately 8.45 femtometres.
1
barn = 100 fm
2
History
The femtometre was adopted by the 11th
''Conférence Générale des Poids et Mesures'', and added to the SI in 1964, using the Danish word for "15" and the similarity in spelling with ''fermi''.
The fermi is named after the
Italian physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
Enrico Fermi
Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" an ...
(1901–1954), one of the founders of nuclear physics. The term was coined by
Robert Hofstadter in a 1956 paper published in ''
Reviews of Modern Physics'' entitled "Electron Scattering and Nuclear Structure". The term is widely used by nuclear and
particle
In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass.
They vary greatly in size or quantity, from ...
physicists. When Hofstadter was awarded the 1961 Nobel Prize in Physics, it subsequently appeared in the text of his 1961 Nobel Lecture, "The electron-scattering method and its application to the structure of nuclei and nucleons" (December 11, 1961).
Hofstadter, Robert, "The electron-scattering method and its application to the structure of nuclei and nucleons," Nobel Lecture (December 11, 1961)
/ref>
References
{{DEFAULTSORT:Femtometre
Metre
de:Meter#Dezimale Vielfache
ru:Фемтометр