Maxwell (unit)

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Maxwell
Unit system Gaussian units
Unit of Magnetic flux
Symbol Mx 
Named after James Clerk Maxwell
Unit conversions
1 Mx in ...... is equal to ...
   Gaussian base units    1 cm3/2⋅g1/2⋅s−1
   SI units    1×10−8 Wb

The maxwell (symbol: Mx) is the CGS (centimetre-gram-second) unit of magnetic flux (Φ).[1]

History[edit]

The unit name honours James Clerk Maxwell, who presented a unified theory of electromagnetism. The maxwell was recommended as a CGS unit at the International Electrical Congress held in 1900 at Paris.[2] This practical unit was previously called a line,[3] reflecting Faraday's conception of the magnetic field as curved lines of magnetic force,[4] which he designated as line of magnetic induction.[5] Kiloline (103 line) and megaline (106 line) were sometimes used because 1 line was very small relative to the phenomena that it was used to measure.[4]

The maxwell was affirmed again unanimously as the unit name for magnetic flux at the Plenary Meeting of the International Electrotechnical Commission in July 1930 at Oslo.[6] In 1933, the Electric and Magnetic Magnitudes and Units committee of the International Electrotechnical Commission recommended to adopt the metre-kilogram-second (MKS) system (Giorgi system), and the name weber was proposed for the practical unit of magnetic flux (Φ), subject to approval of various national committees, which was achieved in 1935.[7] The weber was thus adopted as a practical unit of magnetic flux by the International Electrotechnical Commission.

Definition[edit]

The maxwell is a non-SI unit.[8]

1 maxwell = 1 gauss × cm2

That is, one maxwell is the total flux across a surface of one square centimetre perpendicular to a magnetic field of strength one gauss.

The weber is the related SI unit of magnetic flux, which was defined in 1946.[9]

1 maxwell = 10−8 weber

See also[edit]

References[edit]

  1. ^ International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN 92-822-2213-6, archived (PDF) from the original on 2017-08-14 , p. 128
  2. ^ "Séance de cloture". Congrès International d'électricité. Paris: Gauthier-Villars. 1901. p. 354.  (in French)
  3. ^ Gyllenbok, Jan (2018). "line". Encyclopaedia of Historical Metrology, Weights, and Measures, Volume 1. Birkhäuser. p. 141. ISBN 9783319575988. Retrieved 20 April 2018. 
  4. ^ a b Klein, H.A. (1988) [1974]. The science of measurement: A historical survey. Dover. p. 481. 
  5. ^ Gyllenbok, Jan (2018). "line of magnetic induction". Encyclopaedia of Historical Metrology, Weights, and Measures, Volume 1. Birkhäuser. p. 141. ISBN 9783319575988. Retrieved 20 April 2018. 
  6. ^ Kennelly, A.E. "Conference of the Symbols, Units and Nomenclature (S. U. N.) Commission of the International Union Of Pure and Applied Physics (I. P. U.), At Paris, in July, 1932, and its Results". Proceedings of the National Academy of Sciences of the United States of America. 19 (1): 146. JSTOR 85786. 
  7. ^ Kennelly, A.E. (1935). "I.E.C. adopts MKS system of units". Electrical Engineering. 54: 1377. doi:10.1109/EE.1935.6538821. 
  8. ^ "Non-SI units accepted for use with the SI, and units based on fundamental constants (contd.)". SI Brochure: The International System of Units (SI) [8th edition, 2006; updated in 2014]. Bureau International des Poids et Mesures. Retrieved 19 April 2018. 
  9. ^ International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN 92-822-2213-6, archived (PDF) from the original on 2017-08-14 , p. 144