Mælieiningar

Mælieiningar, or units of measurement, are standardized quantities used to express the magnitude of physical quantities. They provide a common reference that enables accurate communication, calculation, and comparison across science, industry, and daily life.

Most modern systems of mælieiningar are based on the International System of Units (SI). The SI defines seven base units for fundamental quantities: metre for length, kilogram for mass, second for time, ampere for electric current, kelvin for thermodynamic temperature, mole for amount of substance, and candela for luminous intensity. Derived units result from combining base units, such as newton for force (kg·m/s²), joule for energy (kg·m²/s²), and watt for power (kg·m²/s³).

Decimal prefixes express multiples and submultiples of units, for example kilo- (1000), milli- (0.001), micro- (0.000001), and nano- (0.000000001).

History and governance: The metric system emerged in Europe in the 18th and 19th centuries and was formalized into SI in 1960. The system is maintained by the International Bureau of Weights and Measures (BIPM) and is widely adopted worldwide. Some fields and regions still use non-SI units in everyday language, but SI remains the basis for scientific measurement.

Practical aspects: Accurate measurement relies on traceability to national or international standards, regular calibration of instruments, and reporting of measurement uncertainty.