Standardisation of the Unit of Electrical Resistance

This discusses the historical developments that led to the standardisation of the Ohm. Following developments in early electrical telegraphy systems, in 1861 the British Association (BA) set up a committee, which proposed electrical units of resistance, based on the metric system. The committee considered many of the earlier resistance standards, which had been developed in Britain and overseas, before proposing a wire coil standards system, the BA Unit of Resistance, which matched closely the requirements of telegraphic engineers. It finally fabricated several standard resistors in 1865, which still exist today in the London Science Museum. The committee later recommended, in 1872, that the unit of resistance be named the “Ohm,” after the celebrated German physicist and Georg Ohm. These material standards, later became the International Units of 1893, which continued in use until they were superseded by the SI units in 1948.