Convert Dekameter to Femtometer

A dekameter (also spelled decameter) is a metric unit of length equal to ten meters (10 m). It is one of the less commonly used SI prefix units and primarily appears in agricultural, surveying, and atmospheric contexts.

The dekameter was defined alongside the meter when France adopted the metric system in 1795, using the standard SI prefix deca- (from Greek deka, ten) to denote a multiplication by ten.

Dekameters are used in some European agricultural contexts (parcel sizes, field measurements), atmospheric science (cloud heights), and certain track and field events. Modern usage is uncommon outside specialised technical fields.

Adopted in 1795 in France; ratified through the Metre Convention of 1875; remains a recognised SI prefix unit although informally superseded by the more common meter and hectometer in everyday surveying.

A femtometer is a metric unit of length equal to one quadrillionth of a meter (1×10⁻¹⁵ m). It is the standard unit for measuring sub-atomic dimensions, particularly the size of atomic nuclei. The femtometer is also known historically as the fermi.

The femtometer was defined using the SI prefix femto- (from Danish femten, meaning fifteen), adopted by the CGPM in 1964 to denote one quadrillionth. The synonymous name fermi was named after Italian physicist Enrico Fermi.

Femtometers are used to express the size of atomic nuclei (typically 1–10 fm in diameter), the range of strong nuclear forces, and characteristic dimensions in particle physics. The proton charge radius is approximately 0.84 fm.

SI prefix femto- adopted in 1964; the unit became standard in nuclear physics through the late 20th century. The name fermi (after Enrico Fermi) was used informally from the 1950s but officially superseded by femtometer.