The maxwell (symbol: Mx) is the
CGS (centimetre–gram–second) unit of
magnetic flux ().
History
The unit name honours
James Clerk Maxwell
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish physicist and mathematician who was responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism an ...
, who presented a unified theory of
electromagnetism
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...
. The ''maxwell'' was recommended as a CGS unit at the
International Electrical Congress held in 1900 at Paris. This practical unit was previously called a ''line'',
reflecting
Faraday
Michael Faraday (; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic inducti ...
's conception of the magnetic field as curved lines of magnetic force,
which he designated as ''line of magnetic induction''.
''Kiloline'' (10
3 line) and ''megaline'' (10
6 line) were sometimes used because 1 line was very small relative to the phenomena that it was used to measure.
The ''maxwell'' was affirmed again unanimously as the unit name for magnetic flux at the Plenary Meeting of the
International Electrotechnical Commission
The International Electrotechnical Commission (IEC; ) is an international standards organization that prepares and publishes international standards for all electrical, electronics, electronic and related technologies. IEC standards cover a va ...
(IEC) in July 1930 at Oslo. In 1933, the Electric and Magnetic Magnitudes and Units committee of the IEC recommended to adopt the metre–kilogram–second (
MKS) system (
Giorgi system), and the name
weber was proposed for the practical unit of magnetic flux (), subject to approval of various national committees, which was achieved in 1935. The ''weber'' was thus adopted as a practical unit of magnetic flux by the IEC.
Definition
The ''maxwell'' is a non-
SI unit
The International System of Units, internationally known by the abbreviation SI (from French ), is the modern form of the metric system and the world's most widely used system of units of measurement, system of measurement. It is the only system ...
.
:1 maxwell = 1
gauss
Johann Carl Friedrich Gauss (; ; ; 30 April 177723 February 1855) was a German mathematician, astronomer, Geodesy, geodesist, and physicist, who contributed to many fields in mathematics and science. He was director of the Göttingen Observat ...
× (
centimetre
upright=1.35, Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The microwave is in-between 1 meter to 1 millimeter.
A centimetre (International spelling) or centimeter (American ...
)
2
That is, one maxwell is the total flux across a surface of one square centimetre
perpendicular
In geometry, two geometric objects are perpendicular if they intersect at right angles, i.e. at an angle of 90 degrees or π/2 radians. The condition of perpendicularity may be represented graphically using the '' perpendicular symbol'', � ...
to a
magnetic field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...
of strength one gauss.
The
weber is the related SI unit of magnetic flux, which was defined in 1946.
[, p. 144]
: 1 maxwell ≘ 10
−4 tesla × (10
−2 metre
The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of of ...
)
2 = 10
−8 weber
See also
*
Centimetre–gram–second system of units
The centimetre–gram–second system of units (CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unamb ...
*
Gaussian units
Gaussian units constitute a metric system of units of measurement. This system is the most common of the several electromagnetic unit systems based on the centimetre–gram–second system of units (CGS). It is also called the Gaussian unit syst ...
*
Maxwell's equations
Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, Electrical network, electr ...
References
{{DEFAULTSORT:Maxwell (Unit)
Units of magnetic flux
Centimetre–gram–second system of units
James Clerk Maxwell