A line of force in

Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, ...

's extended sense is synonymous with Maxwell's line of induction. According to

J.J. Thomson Sir Joseph John Thomson (18 December 1856 – 30 August 1940) was a British physicist and Nobel Laureate in Physics, credited with the discovery of the electron, the first subatomic particle to be discovered. In 1897, Thomson showed that ...

, Faraday usually discusses ''lines of force'' as chains of polarized particles in a dielectric, yet sometimes Faraday discusses them as having an existence all their own as in stretching across a vacuum.Notes on Recent Researches in Electricity and Magnetism
Joseph John Thomson, James Clerk Maxwell, 1883 In addition to lines of force, J.J. Thomson—similar to Maxwell—also calls them tubes of

electrostatic Electrostatics is a branch of physics that studies electric charges at rest (static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber ...

inductance Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of the ...

, or simply Faraday tubes. From the 20th century perspective, lines of force are energy linkages embedded in a 19th-century unified field theory that led to more mathematically and experimentally sophisticated concepts and theories, including Maxwell's equations, electromagnetic waves, and Einstein's relativity. Lines of force originated with Michael Faraday, whose theory holds that all of reality is made up of force ''itself''. His theory predicts that electricity, light, and gravity have finite propagation delays. The theories and experimental data of later scientific figures such as Maxwell, Hertz, Einstein, and others are in agreement with the ramifications of Faraday's theory. Nevertheless, Faraday's theory remains distinct. Unlike Faraday, Maxwell and others (e.g., J.J. Thomson) thought that light and electricity must propagate through an

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...

. In Einstein's relativity, there is no ether, yet the physical reality of force is much weaker than in the theories of Faraday.

Fields of Force ''Fields of Force: The Development of a world view from Faraday to Einstein'' is a book by William Berkson, published in 1974 by Routledge in the U.K. and John Wiley & Sons in the U.S.. It is an extension of his doctoral thesis, which was superv ...

, William Berkson, 1974 Forces and Fields,

Mary B. Hesse Mary Brenda Hesse FBA (15 October 1924 – 2 October 2016) was an English philosopher of science, latterly a professor in the subject at the University of Cambridge. Biography Mary Hesse was born in Reigate, Surrey, to Ethelbert (Bertie) Thom ...

, 1961 Historian

Nancy J. Nersessian Nancy J. Nersessian is the ''Regents' Professor and Professor of Cognitive Science'' at the Georgia Institute of Technology. Her work tends to be in the areas of the philosophy of science, the history of science, and the psychology of science. She ...

in her paper "Faraday's Field Concept" distinguishes between the ideas of Maxwell and Faraday:

The specific features of Faraday's field concept, in its 'favourite' and most complete form, are that force is a substance, that it is the only substance and that all forces are interconvertible through various motions of the lines of force. These features of Faraday's 'favourite notion' were not carried on. Maxwell, in his approach to the problem of finding a mathematical representation for the continuous transmission of electric and magnetic forces, considered these to be states of stress and strain in a mechanical aether. This was part of the quite different network of beliefs and problems with which Maxwell was working.

Views of Faraday

At first

considered the physical reality of the ''lines of force'' as a possibility, yet several scholars agree that for Faraday their physical reality became a conviction. One scholar dates this change in the year 1838.''The Origins of Field Theory'', L. Pearce Williams (Cornell University), 1966, Random House, p. 88 (a), p.124 (b) Another scholar dates this final strengthening of his belief in 1852. Faraday experimentally studied lines of magnetic force and lines of electrostatic force, showing them not to fit action at a distance models. In 1852 Faraday wrote the pape
"On the Physical Character of the Lines of Magnetic Force"
which examined gravity, radiation, and electricity, and their possible relationships with the transmission medium, transmission propagation, and the receiving entity.

Views of Maxwell

Initially, Maxwell took an agnostic approach in his mathematization of Faraday's theories. This is seen in Maxwell's 1855 and 1856 papers: "On Faraday's Lines of Force" and "On Faraday's Electrotontic State". In the 1864 paper "

A Dynamical Theory of the Electromagnetic Field "A Dynamical Theory of the Electromagnetic Field" is a paper by James Clerk Maxwell on electromagnetism, published in 1865. ''(Paper read at a meeting of the Royal Society on 8 December 1864).'' In the paper, Maxwell derives an electromagnetic wav ...

" Maxwell gives

scientific priority In science, priority is the credit given to the individual or group of individuals who first made the discovery or propose the theory. Fame and honours usually go to the first person or group to publish a new finding, even if several researchers arr ...

of the electromagnetic theory of light to Faraday and his 1846 paper
Thoughts on Ray Vibrations
. Maxwell wrote:

Faraday discovered that when a plane polarized ray traverses a transparent diamagnetic medium in the direction of the lines of magnetic force produced by magnets or currents in the neighborhood, the plane of polarization is caused to rotate.

The conception of the propagation of transverse magnetic disturbances to the exclusion of normal ones is distinctly set forth by Professor Faraday in his "Thoughts on Ray Vibrations." The electromagnetic theory of light, as proposed by him, is the same in substance as that which I have begun to develop in this paper, except that in 1846 there was no data to calculate the velocity of propagation.

Tube of force

Maxwell changed Faraday's phrase ''lines of force'' to ''tubes of force'', when expressing his fluidic assumptions involved in his mathematization of Faraday's theories. A tube of force, also called a tube of electrostatic induction or field tube, are the ''lines of electric force'' which moves so that its beginning traces a closed curve on a positive surface, its end will trace a corresponding closed curve on the negative surface, and the line of force itself will generate an inductive tubular surface. Such a tube is called a "

Solenoid upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whose ...

". There is a pressure at right angles to a tube of force of one half the product of the dielectric and magnetic density. If through the growth of a field the tubes of force are spread sideways or in width there is a magnetic reaction to that growth in intensity of electric current. However, if a tube of force is caused to move endwise there is little or no drag to limit velocity. Tubes of force are absorbed by bodies imparting momentum and gravitational mass. Tubes of force are a group of electric lines of force.

Magnetic curves

Early on in his research (circa 1831), Faraday calls the patterns of apparently continuous curves traced out in metallic filings near a magnet ''magnetic curves''. Later on he refers to them as just an instance of magnetic lines of force or simply lines of force. Eventually Faraday would also begin to use the phrase "magnetic field". Colin A. Russell, ''Michael Faraday: Physics and Faith'', 2000,

Oxford University Press Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books ...

, pp. 99-100 Chapter 9 "Electromagnetism: 'At Play in the Fields of the Lord'

Other relevant papers

*Faraday, Michael, "Thoughts on Ray Vibrations", Philosophical Magazine, May 1846, or Experimental Researches, iii, p. 447 *Faraday, Michael, ''Experimental Researches,'' Series 19.

Notes