What is Angstrom?
{{otheruses}} An '''angstrom''' or '''ångström''' (symbol [[Å]])<ref>{{pronEng|ˈæŋstrəm}}; [[Swedish language|Swedish]]: {{IPA2|ˈɔ̀ŋstrœm}}</ref> is a [[unit of length]] that equals 0.1 nanometer ([[nanometre|nm]]). It can be written in [[scientific notation]] as 1×10<sup>−10</sup>&nbsp;m (normalized notation) or {{nowrap|1 E-10 m}} (exponential notation) — both mean {{nowrap|1/10,000,000,000 meters}}. It is sometimes used to express the sizes of [[atom]]s, lengths of [[chemical bond]]s and [[spectrum|visible-light spectra]], and dimensions of parts of [[integrated circuit]]s. For example, a single atom is about two ångströms wide, and a human hair is about a million ångströms thick. == History == The ångström is named after the [[Sweden|Swedish]] [[physicist]] [[Anders Jonas Ångström]] (1814–1874), one of the founders of [[spectroscopy]] who is known also for studies of [[astrophysics]], flow of [[heat]], the earth's [[magnetism|magnetic field]], and the [[aurora borealis]]. In 1868, Ångström created a spectrum chart of [[solar radiation]] that expresses each [[wavelength]] in the [[electromagnetic spectrum|spectrum]] of sunlight in multiples of one ten-millionth of a [[millimetre]], or 1{{e|−10}} [[metre]]s. This unit of [[length]] later became known as the ångström, Å. Human beings can see light having [[wavelength]]s ranging from about 4,000 ångströms (violet) to 7,000 ångströms (deep red), so the ångström was a convenient unit of measurement. Because of its closeness to the scale of atoms and molecules it was also popular in [[chemistry]] and [[crystallography]]. Today, the use of the ångström as a unit is less popular than it used to be, and the nanometre ([[nm]]) is often used instead (The ångström is officially discouraged by the International Committee for Weights and Measures, and by the American National Standard for Metric Practice.) == References == {{reflist}} {{DEFAULTSORT:Angstrom}} [[Category:Units of length]]