Now almost everyone knows that the electric and magnetic fields are directly related to each other.Even there is a special branch of physics that studies the electromagnetic phenomena.But in the 19th century until it was formulated by Maxwell's electromagnetic theory, everything was completely different.It was believed, for example, that the electric fields are inherent only in particles and bodies, have an electric charge and magnetic properties - a completely different field of science.
In 1864, the famous British physicist JC Maxwell points to a direct correlation of electric and magnetic phenomena.The discovery has been called "the theory of the electromagnetic field of Maxwell."Thanks to her, managed to solve a number of intractable from the standpoint of electrodynamics that time, questions.
most high-profile discoveries are always based on the work of previous researchers.Maxwell's theory - is no exception.A distinctive feature is that Maxwell has significantly expanded the results obtained by his predecessors.For example, he pointed out that the experience of Faraday can be used not only to a closed loop of a conductive material, but consists of any material.In this case, the circuit is indicative of a solenoidal electric field, which affects not only the metal lattice.At this point of view when you are in the field of dielectric material is more correct to talk about the polarization currents.They also perform the work, which consists in heating the material to a predetermined temperature.
first suspected the connection of electric and magnetic phenomena appeared in 1819.H. Oersted said that if the vicinity of the conductor with a current position the compass, the direction of the arrow deviates from the North Pole.
In 1824 A. Ampere formulated the law of interaction of conductors, later called "Ampere's Law."
And finally, in 1831, Faraday gave the appearance of current in the circuit is located in a changing magnetic field.
Maxwell's theory is designed to solve the basic problem of electrodynamics: a known spatial distribution of electric charges (currents) can determine some characteristics of the generated magnetic and electric fields.This theory does not consider themselves the mechanisms underlying the phenomena occurring.
Maxwell's theory is closely spaced to charge, as in the system of equations is considered that electromagnetic interactions occur with the speed of light, regardless of the environment.An important feature of the theory is the fact that it considered the basis of such fields that:
- generated relatively large currents and charges distributed on a large scale (many times the size of an atom or molecule);
- alternating magnetic and electric field changes faster than the period of the processes within the molecules;
- calculated the distance between the point of the space and the source of the field is greater than the size of atoms (molecules).
All of this suggests that Maxwell's theory applies primarily to the phenomena of the macrocosm.Modern physics explains more processes from the point of view of quantum theory.In the formulas of Maxwell quantum manifestations are not counted.Nevertheless, the use of Maxwell's system of equations to successfully meet certain challenges.Interestingly, as the density of the recorded currents and electrical charges, it is theoretically possible to have them the same, but a magnetic nature.To this in 1831 have Dirac, denoting their magnetic monopoles.In general, the basic tenets of the theory of the following:
- magnetic field is an alternating electric field;
- variable magnetic field generates an electric field of the vortex nature.