Maxwelln.²

Brit.

/ˈmakswɛl/,

/ˈmaksw(ə)l/, U.S.

/ˈmækswəl/

Origin: From a proper name. Etymon: proper name Maxwell.

Etymology: < the name of James Clerk Maxwell (1831–79), Scottish physicist (see below). With sense 3 compare French Maxwell (1900, Congrès d'électricité de Paris).Maxwell first propounded his ‘demon’ paradox (see sense 1a) in a letter to P. G. Tait of 11 Dec. 1867, but there referred to ‘a finite being’, not a ‘demon’. In his published Theory of Heat (1871) Maxwell describes the being as having ‘faculties..so sharpened that he can follow every molecule in its course’ (pp. 308–9), but still does not use the term ‘demon’. In a paper of 1874 ( Proc. Royal Soc. Edinb. 8 325–34), W. Thomson refers to ‘an army of Maxwell's “intelligent demons”’, and makes it clear that he thinks the phrase is Maxwell's; but Maxwell ascribed the term ‘demon’ to Thomson, and did not approve of it himself. See P. M. Harman Sci. Lett. & Papers J. C. Maxwell (1990) I. 332, (2002) III. 185–6.

Physics.

I. Compounds.

a. Maxwell's demon n. (also Maxwell demon) an entity imagined by Maxwell as allowing only fast-moving molecules to pass through a hole in one direction and only slow-moving ones in the other direction, so that if the hole is in a partition dividing a gas-filled vessel, one side becomes warmer and the other cooler, in contradiction of the second law of thermodynamics.

ΘΚΠ

the world > matter > physics > mechanics > dynamics > thermodynamics > [noun] > imagined being contradicting second law

Maxwell's demon1879

1879 W. Thomson in Proc. Royal Inst. 9 113 Clerk Maxwell's ‘demon’ is a creature of imagination.., invented to help us to understand the ‘Dissipation of Energy’ in nature.

1885 Science 31 July 83/1 (heading) Maxwell's demons.

1956 E. H. Hutten Lang. Mod. Physics iv. 152 It would require a Maxwell demon..to select the rapidly moving molecules according to their velocity and concentrate them in one corner of the vessel.

1971 Sci. Amer. Sept. 182/2 Maxwell's demon became an intellectual thorn in the side of thermodynamicists for almost a century. The challenge to the second law of thermodynamics was this: Is the principle of the increase of entropy in all spontaneous processes invalid where intelligence intervenes?

1988 Nature 27 Oct. 779/2 Questions about the energy needed in measurement began with Maxwell's demon.

b. Maxwell's law n. (also Maxwell law) a law in classical physics giving the probabilities of different velocities for the molecules of a gas in equilibrium.

ΘΚΠ

the world > matter > physics > mechanics > types of motion > [noun] > kinetic theory of heat or gases > specific law

Maxwell's law1899

1899 R. E. Baynes tr. O. E. Meyer Kinetic Theory of Gases iii. 48 That this extension of Maxwell's law to compound molecules is admissible was first recognised by Boltzmann.

1943 H. Margenau & G. M. Murphy Math. Physics & Chem. xii. 432 The Maxwell law for the distribution of velocities in an ideal gas.

1963 G. Troup Masers & Lasers (ed. 2) iii. 37 In a gas, the molecules possess randomly directed velocities which depend on the temperature T and which are distributed about a most probable velocity according to Maxwell's law.

c. Maxwell's distribution n. (also Maxwell distribution) the distribution of molecular velocities predicted by Maxwell's law, the number with a velocity between v and v + dv being proportional to exp (−½mv²/kT)v²dv (where m is the mass of a molecule, k is Boltzmann's constant, and T is the absolute temperature).

ΘΚΠ

the world > matter > physics > mechanics > types of motion > [noun] > kinetic theory of heat or gases > specific law > distribution predicted by

Maxwell's distribution1899

Maxwell–Boltzmann distribution1927

1899 R. E. Baynes tr. O. E. Meyer Kinetic Theory of Gases 370 If the number of particles is limited..Maxwell's distribution cannot exist at every moment, but will occur with exactness only when the changing states which succeed each other in the course of a sufficiently long period are all taken into account together.

1955 F. L. Friedman & V. F. Weisskopf in W. Pauli Niels Bohr & Devel. Physics 138 The spectrum of neutrons and protons emitted from nuclei bombarded with neutrons of 14 Mev or with protons of similar energy fits approximately the predicted Maxwell distribution of an evaporating compound nucleus.

1986 P. W. Atkins Physical Chem. (ed. 3) xviii. 435 This profile reflects the Maxwell distribution of molecular speeds parallel to the line of sight.

d. Maxwell bridge n. (also Maxwell's bridge) a four-armed alternating current bridge used for measuring inductance in terms of capacitance and resistance, or for measuring capacitance in terms of inductance and resistance.

ΘΚΠ

the world > matter > physics > electromagnetic radiation > electricity > resistance > [noun] > instrument used in measuring > in form of bridge

bridge1865

Wheatstone bridge1865

wire bridge1880

post-office bridge1890

post office box1894

Kelvin double bridge1896

Maxwell bridge1907

1907 Bull. Bureau of Standards (U.S.) 3 437 A pair of coaxial cylinders was..so joined to the Maxwell bridge that the electromagnetic capacity..could be measured.

1970 D. F. Shaw Introd. Electronics (ed. 2) iv. 69 An extension of Maxwell's bridge by Anderson enables a balance to be made with resistances as the only variable components.

1999 Electronics Now (Nexis) 1 July 40 The Maxwell bridge is often used to measure unknown values of inductance..because the balance equations are totally independent of frequency.

e. Maxwell's equation n. (also Maxwell equation) each of a set of four linear partial differential equations which summarize the classical properties of the electromagnetic field and relate space and time derivatives of the electric and magnetic field vectors, the electric displacement vector, and the magnetic induction vector, and also involve the electric current and charge densities; now usually in plural.Maxwell published eight equations of the electromagnetic field on pp. 480–6 of his paper ‘A Dynamical Theory of the Electromagnetic Field’ ( Philos. Trans. Royal Soc. (1865) 155 459–512). But the four equations now known as Maxwell's equations owe their form to O. Heaviside. Heaviside published them as a more useful and compact set of Maxwell's eight equations in a series of papers published in the Electrician in 1885, specifically in the issues of 21 Feb., 14 Mar., and 12 June (republished in his collected Electr. Papers (1892) I: see pp. 447, 452, and 475).

ΘΚΠ

the world > matter > physics > electromagnetic radiation > electricity > electrically induced magnetism > [noun] > field > equation, formula

field equation1889

Maxwell's equation1907

Poynting vector1913

1907 Sci. Abstr. A. 10 1295 The principle of relativity in conjunction with Maxwell's equation leads to the conclusion that the inertia of a body changes in a quite determinate manner with its energy-content.

1925 H. C. Booth tr. F. Auerbach Mod. Magnetics (U.K. ed.) ix. 242 The magnetization current i is measured and the Maxwell equation is relied on, according to which the total magnetomotive force is determined by the number of ampere turns in the magnetizing coils.

1962 D. R. Corson & P. Lorrain Introd. Electromagn. Fields iii. 101 If the symmetry of the [electrostatic] field is simple and if the charge density ρ is zero, as it often is, we can usually integrate the Maxwell equation ∇·D = ρ to find the displacement vector D.

1964 E. A. Power Introd. Quantum Electrodynamics i. 4 Maxwell's equations are not invariant under Galilean invariance and thus are not valid in all inertial frames. Historically this was a most important result leading to special relativity.

1981 A. Salam in J. H. Mulvey Nature of Matter v. 121 The presence of monopoles in the theory would also complete a symmetry in the Maxwell equations of electromagnetism.

2. attributive and in the genitive. In various miscellaneous terms designating concepts arising from Maxwell's work.

ΚΠ

1902 Encycl. Brit. XXXIII. 213/1 This wider theory [of the electric telegraph] is grounded upon Maxwell's theory of electromagnetic radiation.

1929 T. M. Lowry & S. Sugden Physical Chem. 19 According to Maxwell's principle of equipartition of energy, each degree of freedom calls for an equal increment of internal energy.

1935 C. J. Smith Intermediate Physics (ed. 2) v. xliv. 711 Maxwell's Rule... If an observer imagines that a corkscrew is being driven in the direction of the current, a north pole, placed in the field, will move in the same direction as the screw being turned.

1962 J. Dougall tr. M. Born Atomic Physics (ed. 7) iii. 59 According to Maxwell's electromagnetic theory, light..consists of a periodically variable, electromagnetic alternating field.

1986 P. W. Atkins Physical Chem. (ed. 3) vi. 123 The fact that H, G, and A are state functions can be used to derive three more Maxwell relations.

II. Simple uses.

3. Usually in form maxwell. A unit of magnetic flux in the cgs system, equal to the flux through an area of one square centimetre normal to a uniform induction of one gauss.In the International System of Units the unit of magnetic flux is the weber (= 10⁸ maxwells).

ΘΚΠ

the world > matter > physics > electromagnetic radiation > electricity > electrically induced magnetism > [noun] > magnetic flux > unit of flux

weber1891

Maxwell1900

Tesla1960

T1964

1900 Nature 30 Aug. 414/1 The Commission proposes to assign to the unit of magnetic flux, of which the magnitude will be subsequently defined, the name of Maxwell.

1924 A. Still Elem. Electr. Design iv. 68 It is desired to estimate the total flux in maxwells carried by a closed circular iron ring.

1959 R. L. Shrader Electronic Communication iii. 72 The gauss is the flux density in maxwells per square centimeter.

1992 S. P. Maran Astron. & Astrophysics Encycl. 641/1 Unseen hydrodynamic forces must then be able to build up a total flux of 10²² Maxwells.

This entry has been updated (OED Third Edition, March 2001; most recently modified version published online March 2022).

单词	maxwell
释义	Maxwelln.¹ Brit. /ˈmakswɛl/, /ˈmaksw(ə)l/, U.S. /ˈmækswəl/ Origin: From a proper name. Etymon: proper name Maxwell. Etymology: < the name of Sir Charles William Maxwell, British soldier and explorer (?1775–1848), who procured the first specimen of the animal from Sierra Leone. †1. Maxwell's antelope n. = Maxwell's duiker n. at sense 2. Obsolete. rare. ΘΚΠ the world > animals > mammals > group Ungulata (hoofed) > group Ruminantia (sheep, goats, cows, etc.) > antelope > [noun] > subfamily Cephalophinae (duiker) duiker1777 diving goat1786 Maxwell's antelope1827 coquetoon1846 Maxwell's duiker1905 1827 E. Griffith et al. Cuvier's Animal Kingdom IV. 267 Maxwell's Antelope. (A. Maxwellii.) A specimen somewhat inferior in size was brought home from Sierra Leone by Colonel Charles Maxwell. 2. Maxwell's duiker n. a small grey or brown duiker, Cephalophus (or Philantomba) maxwellii, of West African forests. ΘΚΠ the world > animals > mammals > group Ungulata (hoofed) > group Ruminantia (sheep, goats, cows, etc.) > antelope > [noun] > subfamily Cephalophinae (duiker) duiker1777 diving goat1786 Maxwell's antelope1827 coquetoon1846 Maxwell's duiker1905 1905 P. L. Sclater & M. R. O. Thomas Bk. Antelopes I. 182 Maxwell's Duiker appears to extend from Senegal and Gambia all along the west coast of Africa to the mouths of the Niger. 1960 Times 29 Sept. (Nigeria Suppl.) p. xxi/4 The little Maxwell's duiker..is everywhere abundant. 1984 D. Macdonald Encycl. Mammals II. 557/1 (caption) Male Maxwell's duiker..about to rub his preorbital gland on a rival before fighting. This entry has been updated (OED Third Edition, March 2001; most recently modified version published online March 2022). Maxwelln.² Brit. /ˈmakswɛl/, /ˈmaksw(ə)l/, U.S. /ˈmækswəl/ Origin: From a proper name. Etymon: proper name Maxwell. Etymology: < the name of James Clerk Maxwell (1831–79), Scottish physicist (see below). With sense 3 compare French Maxwell (1900, Congrès d'électricité de Paris).Maxwell first propounded his ‘demon’ paradox (see sense 1a) in a letter to P. G. Tait of 11 Dec. 1867, but there referred to ‘a finite being’, not a ‘demon’. In his published Theory of Heat (1871) Maxwell describes the being as having ‘faculties..so sharpened that he can follow every molecule in its course’ (pp. 308–9), but still does not use the term ‘demon’. In a paper of 1874 ( Proc. Royal Soc. Edinb. 8 325–34), W. Thomson refers to ‘an army of Maxwell's “intelligent demons”’, and makes it clear that he thinks the phrase is Maxwell's; but Maxwell ascribed the term ‘demon’ to Thomson, and did not approve of it himself. See P. M. Harman Sci. Lett. & Papers J. C. Maxwell (1990) I. 332, (2002) III. 185–6. Physics. I. Compounds. 1. a. Maxwell's demon n. (also Maxwell demon) an entity imagined by Maxwell as allowing only fast-moving molecules to pass through a hole in one direction and only slow-moving ones in the other direction, so that if the hole is in a partition dividing a gas-filled vessel, one side becomes warmer and the other cooler, in contradiction of the second law of thermodynamics. ΘΚΠ the world > matter > physics > mechanics > dynamics > thermodynamics > [noun] > imagined being contradicting second law Maxwell's demon1879 1879 W. Thomson in Proc. Royal Inst. 9 113 Clerk Maxwell's ‘demon’ is a creature of imagination.., invented to help us to understand the ‘Dissipation of Energy’ in nature. 1885 Science 31 July 83/1 (heading) Maxwell's demons. 1956 E. H. Hutten Lang. Mod. Physics iv. 152 It would require a Maxwell demon..to select the rapidly moving molecules according to their velocity and concentrate them in one corner of the vessel. 1971 Sci. Amer. Sept. 182/2 Maxwell's demon became an intellectual thorn in the side of thermodynamicists for almost a century. The challenge to the second law of thermodynamics was this: Is the principle of the increase of entropy in all spontaneous processes invalid where intelligence intervenes? 1988 Nature 27 Oct. 779/2 Questions about the energy needed in measurement began with Maxwell's demon. b. Maxwell's law n. (also Maxwell law) a law in classical physics giving the probabilities of different velocities for the molecules of a gas in equilibrium. ΘΚΠ the world > matter > physics > mechanics > types of motion > [noun] > kinetic theory of heat or gases > specific law Maxwell's law1899 1899 R. E. Baynes tr. O. E. Meyer Kinetic Theory of Gases iii. 48 That this extension of Maxwell's law to compound molecules is admissible was first recognised by Boltzmann. 1943 H. Margenau & G. M. Murphy Math. Physics & Chem. xii. 432 The Maxwell law for the distribution of velocities in an ideal gas. 1963 G. Troup Masers & Lasers (ed. 2) iii. 37 In a gas, the molecules possess randomly directed velocities which depend on the temperature T and which are distributed about a most probable velocity according to Maxwell's law. c. Maxwell's distribution n. (also Maxwell distribution) the distribution of molecular velocities predicted by Maxwell's law, the number with a velocity between v and v + dv being proportional to exp (−½mv²/kT)v²dv (where m is the mass of a molecule, k is Boltzmann's constant, and T is the absolute temperature). ΘΚΠ the world > matter > physics > mechanics > types of motion > [noun] > kinetic theory of heat or gases > specific law > distribution predicted by Maxwell's distribution1899 Maxwell–Boltzmann distribution1927 1899 R. E. Baynes tr. O. E. Meyer Kinetic Theory of Gases 370 If the number of particles is limited..Maxwell's distribution cannot exist at every moment, but will occur with exactness only when the changing states which succeed each other in the course of a sufficiently long period are all taken into account together. 1955 F. L. Friedman & V. F. Weisskopf in W. Pauli Niels Bohr & Devel. Physics 138 The spectrum of neutrons and protons emitted from nuclei bombarded with neutrons of 14 Mev or with protons of similar energy fits approximately the predicted Maxwell distribution of an evaporating compound nucleus. 1986 P. W. Atkins Physical Chem. (ed. 3) xviii. 435 This profile reflects the Maxwell distribution of molecular speeds parallel to the line of sight. d. Maxwell bridge n. (also Maxwell's bridge) a four-armed alternating current bridge used for measuring inductance in terms of capacitance and resistance, or for measuring capacitance in terms of inductance and resistance. ΘΚΠ the world > matter > physics > electromagnetic radiation > electricity > resistance > [noun] > instrument used in measuring > in form of bridge bridge1865 Wheatstone bridge1865 wire bridge1880 post-office bridge1890 post office box1894 Kelvin double bridge1896 Maxwell bridge1907 1907 Bull. Bureau of Standards (U.S.) 3 437 A pair of coaxial cylinders was..so joined to the Maxwell bridge that the electromagnetic capacity..could be measured. 1970 D. F. Shaw Introd. Electronics (ed. 2) iv. 69 An extension of Maxwell's bridge by Anderson enables a balance to be made with resistances as the only variable components. 1999 Electronics Now (Nexis) 1 July 40 The Maxwell bridge is often used to measure unknown values of inductance..because the balance equations are totally independent of frequency. e. Maxwell's equation n. (also Maxwell equation) each of a set of four linear partial differential equations which summarize the classical properties of the electromagnetic field and relate space and time derivatives of the electric and magnetic field vectors, the electric displacement vector, and the magnetic induction vector, and also involve the electric current and charge densities; now usually in plural.Maxwell published eight equations of the electromagnetic field on pp. 480–6 of his paper ‘A Dynamical Theory of the Electromagnetic Field’ ( Philos. Trans. Royal Soc. (1865) 155 459–512). But the four equations now known as Maxwell's equations owe their form to O. Heaviside. Heaviside published them as a more useful and compact set of Maxwell's eight equations in a series of papers published in the Electrician in 1885, specifically in the issues of 21 Feb., 14 Mar., and 12 June (republished in his collected Electr. Papers (1892) I: see pp. 447, 452, and 475). ΘΚΠ the world > matter > physics > electromagnetic radiation > electricity > electrically induced magnetism > [noun] > field > equation, formula field equation1889 Maxwell's equation1907 Poynting vector1913 1907 Sci. Abstr. A. 10 1295 The principle of relativity in conjunction with Maxwell's equation leads to the conclusion that the inertia of a body changes in a quite determinate manner with its energy-content. 1925 H. C. Booth tr. F. Auerbach Mod. Magnetics (U.K. ed.) ix. 242 The magnetization current i is measured and the Maxwell equation is relied on, according to which the total magnetomotive force is determined by the number of ampere turns in the magnetizing coils. 1962 D. R. Corson & P. Lorrain Introd. Electromagn. Fields iii. 101 If the symmetry of the [electrostatic] field is simple and if the charge density ρ is zero, as it often is, we can usually integrate the Maxwell equation ∇·D = ρ to find the displacement vector D. 1964 E. A. Power Introd. Quantum Electrodynamics i. 4 Maxwell's equations are not invariant under Galilean invariance and thus are not valid in all inertial frames. Historically this was a most important result leading to special relativity. 1981 A. Salam in J. H. Mulvey Nature of Matter v. 121 The presence of monopoles in the theory would also complete a symmetry in the Maxwell equations of electromagnetism. 2. attributive and in the genitive. In various miscellaneous terms designating concepts arising from Maxwell's work. ΚΠ 1902 Encycl. Brit. XXXIII. 213/1 This wider theory [of the electric telegraph] is grounded upon Maxwell's theory of electromagnetic radiation. 1929 T. M. Lowry & S. Sugden Physical Chem. 19 According to Maxwell's principle of equipartition of energy, each degree of freedom calls for an equal increment of internal energy. 1935 C. J. Smith Intermediate Physics (ed. 2) v. xliv. 711 Maxwell's Rule... If an observer imagines that a corkscrew is being driven in the direction of the current, a north pole, placed in the field, will move in the same direction as the screw being turned. 1962 J. Dougall tr. M. Born Atomic Physics (ed. 7) iii. 59 According to Maxwell's electromagnetic theory, light..consists of a periodically variable, electromagnetic alternating field. 1986 P. W. Atkins Physical Chem. (ed. 3) vi. 123 The fact that H, G, and A are state functions can be used to derive three more Maxwell relations. II. Simple uses. 3. Usually in form maxwell. A unit of magnetic flux in the cgs system, equal to the flux through an area of one square centimetre normal to a uniform induction of one gauss.In the International System of Units the unit of magnetic flux is the weber (= 10⁸ maxwells). ΘΚΠ the world > matter > physics > electromagnetic radiation > electricity > electrically induced magnetism > [noun] > magnetic flux > unit of flux weber1891 Maxwell1900 Tesla1960 T1964 1900 Nature 30 Aug. 414/1 The Commission proposes to assign to the unit of magnetic flux, of which the magnitude will be subsequently defined, the name of Maxwell. 1924 A. Still Elem. Electr. Design iv. 68 It is desired to estimate the total flux in maxwells carried by a closed circular iron ring. 1959 R. L. Shrader Electronic Communication iii. 72 The gauss is the flux density in maxwells per square centimeter. 1992 S. P. Maran Astron. & Astrophysics Encycl. 641/1 Unseen hydrodynamic forces must then be able to build up a total flux of 10²² Maxwells. This entry has been updated (OED Third Edition, March 2001; most recently modified version published online March 2022). < n.¹1827n.²1879
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Maxwelln.1

Maxwelln.2

Maxwelln.¹

Maxwelln.²