Overview. The gauss (symbol G) is a unit used to quantify magnetic flux density, often called magnetic induction or simply the magnetic field in practical contexts. It originates in the centimetre–gram–second (CGS) system and remains in use alongside SI measurements in certain scientific and engineering areas. For a general description of the phenomenon it measures, see magnetic field.

Definition and relationships

By definition, one gauss equals one maxwell per square centimetre. In CGS notation this is written as 1 G = 1 Mx cm⁻2; the related unit maxwell denotes magnetic flux. In the International System of Units (SI), magnetic flux density is measured in tesla. The conversion is straightforward: 1 tesla equals 10,000 gauss, so 1 G = 10⁻4 T. For conversion references see tesla–gauss relations.

History and name

The name honours the German mathematician and physicist Carl Friedrich Gauss. Historical notes and biographical material about him can be found at several resources: Gauss biography (math), Gauss (physics) and further background Carl Friedrich Gauss. The unit emerged as part of 19th- and early 20th-century efforts to standardize electromagnetic quantities within CGS.

Uses and examples

Gauss is commonly used where CGS units persist or where values are conveniently expressed at that scale. Typical magnitudes include:

  • Earth's near-surface magnetic field: on the order of 0.25–0.65 G (several tenths of a gauss).
  • Small laboratory magnets and many consumer magnet specifications are often given in gauss.
  • High-field devices such as MRI scanners are specified in tesla; a 1.5 T scanner therefore corresponds to about 15,000 G.

Distinctions and practical notes

In magnetism it is useful to distinguish magnetic flux density (B), measured in gauss or tesla, from magnetic field strength (H), which in CGS is measured in oersted. Converting between CGS and SI requires care with factors of 4π in contexts involving material magnetization and permeability; for general engineering and laboratory work the simple 1 G = 10⁻4 T conversion suffices for numerical comparisons.

Although SI units are the international standard for scientific publication and most instrumentation, gauss remains a familiar and convenient unit in many applied fields and historical literature. For further technical reading consult introductory texts or the linked topic on magnetic field and unit conversion resources such as tesla and gauss guides.