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History of electricity

Electricity, a set of phenomena caused by the existence, movement and interaction of electrically charged bodies or particles. The interaction of electric charges is carried out with the help of electro magnetic field(in the case of immobile electric charges - an electrostatic field).

Moving charges (electric current), along with an electric one, also excite a magnetic field, that is, they generate an electromagnetic field through which electromagnetic interaction is carried out (the doctrine of magnetism is an integral part of the general doctrine of electricity). Electromagnetic phenomena are described by classical electrodynamics, which is based on the Maxwell equations

The laws of the classical theory of electricity cover a huge set of electromagnetic processes. Among the 4 types of interactions (electromagnetic, gravitational, strong and weak) that exist in nature, electromagnetic take the first place in terms of breadth and variety of manifestations. This is due to the fact that all bodies are built of electrically charged particles of opposite signs, the interactions between which, on the one hand, are many orders of magnitude more intense than gravitational and weak ones, and, on the other hand, are long-range, unlike strong interactions. The structure of atomic shells, the adhesion of atoms into molecules (chemical forces) and the formation of condensed matter are determined by electromagnetic interaction.

The simplest electrical and magnetic phenomena have been known since ancient times. Minerals were found that attracted pieces of iron, and it was also found that amber (Greek electron, elektron, hence the term electricity), rubbed on wool, attracts light objects (electrification by friction). However, it was not until 1600 that W. Gilbert first established the distinction between electrical and magnetic phenomena. He discovered the existence of magnetic poles and their inseparability from each other, and also established that the globe is a giant magnet.

In the XVII - 1st half of the XVIII centuries. numerous experiments were carried out with electrified bodies, the first electrostatic machines based on electrification by friction were built, the existence of electric charges of two kinds was established (C. Dufay), and the electrical conductivity of metals was discovered (the English scientist S. Gray). With the invention of the first capacitor - Leiden jar(1745) - it became possible to accumulate large electric charges. In 1747-53, Franklin set forth the first consistent theory of electrical phenomena, finally established the electrical nature of lightning, and invented the lightning rod.

In the 2nd half of the XVIII century. the quantitative study of electrical and magnetic phenomena began. The first measuring instruments- electroscopes of various designs, electrometers. G. Cavendish (1773) and S. Coulomb (1785) experimentally established the law of interaction of motionless point electric charges (Cavendish's works were published only in 1879).

This basic law of electrostatics (Coulomb's law) for the first time made it possible to create a method for measuring electric charges by the forces of interaction between them. Coulomb also established the law of interaction between the poles of long magnets and introduced the concept of magnetic charges concentrated at the ends of magnets.

The next stage in the development of the science of electricity is associated with the discovery at the end of the 18th century. L. Galvani "animal electricity" and works A. Volta who invented the first source electric current- a galvanic cell (the so-called volt column, 1800), which creates a continuous (constant) current for a long time. In 1802, V.V. Petrov, having built a galvanic cell of much greater power, discovered the electric arc, investigated its properties and pointed out the possibility of using it for lighting, as well as for melting and welding metals. G. Davy by electrolysis aqueous solutions alkalis received (1807) previously unknown metals - sodium and potassium. J, P. Joule established (1841) that the amount of heat released in the conductor by electric current is proportional to the square of the current strength; this law was substantiated (1842) by the exact experiments of E.H. Lenz (the Joule-Lenz law).

G. Ohm established (1826) the quantitative dependence of the electric current on the voltage in the circuit. KF Gauss formulated (1830) the fundamental theorem of electrostatics.

The most fundamental discovery was made by H. Oersted in 1820; he discovered the action of an electric current on a magnetic needle - a phenomenon that testified to the connection between electricity and magnetism. Following this, in the same year, A.M.Ampere established the law of interaction of electric currents (Ampere's law). He also showed that the properties of permanent magnets can be explained on the basis of the assumption that constant electric currents (molecular currents) circulate in the molecules of magnetized bodies. Thus, according to Ampère, all magnetic phenomena are reduced to interactions of currents, while magnetic charges do not exist. Since the discoveries of Oersted and Ampère, the doctrine of magnetism has become an integral part of the doctrine of electricity.

From the 2nd quarter of the 19th century. began the rapid penetration of electricity into technology. In the 20s. the first electromagnets appeared. One of the first uses of electricity was the telegraph apparatus, in the 30s and 40s. electric motors and current generators were built;

In the 30-40s. 19th century M. Faraday, the creator of the general doctrine of electromagnetic phenomena, in which all electrical and magnetic phenomena are considered from a single point of view, made a great contribution to the development of the science of electricity. With the help of experiments, he proved that the effects of electric charges and currents do not depend on the method of their production [before Faraday, they distinguished between "ordinary" (obtained by electrification by friction), atmospheric, "galvanic", magnetic, thermoelectric, "animal" and other types of electrical energy. ].

Arago experiment ("magnetism of rotation").

In 1831, Faraday discovered electromagnetic induction - the excitation of an electric current in a circuit located in an alternating magnetic field. This phenomenon (observed in 1832 also by J. Henry) forms the foundation of electrical engineering. In 1833-34 Faraday established the laws of electrolysis; these works of his laid the foundation for electrochemistry. Later, trying to find the relationship between electrical and magnetic phenomena and optical ones, he discovered the polarization of dielectrics (1837), the phenomena of paramagnetism and diamagnetism (1845), the magnetic rotation of the plane of polarization of light (1845), etc.

Faraday first introduced the concept of electric and magnetic fields. He denied the concept of long-range action, whose proponents believed that bodies directly (through the void) at a distance act on each other.

According to Faraday's ideas, the interaction between charges and currents is carried out through intermediate agents: charges and currents create electric or (respectively) magnetic fields in the surrounding space, with the help of which the interaction is transmitted from point to point (the concept of short-range action). His ideas about electric and magnetic fields were based on the concept of lines of force, which he considered as mechanical formations in a hypothetical medium - ether, similar to stretched elastic threads or cords.

Faraday's ideas about the reality of the electromagnetic field were not immediately recognized. The first mathematical formulation of the laws of electromagnetic induction was given by F. Neumann in 1845 in the language of the concept of long-range action.

He also introduced important concepts of the coefficients of self- and mutual induction of currents. The meaning of these concepts was fully revealed later, when W. Thomson (Lord Kelvin) developed (1853) the theory of electrical oscillations in a circuit consisting of a capacitor (capacitance) and a coil (inductance).
Of great importance for the development of the doctrine of electricity was the creation of new instruments and methods. electrical measurements, as well as a unified system of electrical and magnetic units of measurement, created by Gauss and W. Weber.

In 1846, Weber pointed out the connection between the current strength and the density of electric charges in a conductor and the speed of their orderly movement. He also established the law of interaction of moving point charges, which contained a new universal electrodynamic constant, which is the ratio of electrostatic and electromagnetic units of charge and has the dimension of speed.

In the experimental determination (Weber and f. Kohlrausch, 1856) of this constant, a value close to the speed of light was obtained; this was a definite indication of the connection between electromagnetic phenomena and optical ones.

In 1861-73 the doctrine of electricity was developed and completed in the works of J. K. Maxwell. Based on the empirical laws of electromagnetic phenomena and introducing the hypothesis of the generation of a magnetic field by an alternating electric field, Maxwell formulated the fundamental equations of classical electrodynamics, named after him. At the same time, like Faraday, he considered electromagnetic phenomena as some form of mechanical processes in the ether.

The main new consequence of these equations is the existence of electromagnetic waves propagating at the speed of light. Maxwell's equations formed the basis of the electromagnetic theory of light. Decisive confirmation of Maxwell's theory was found in 1886-89, when G. Hertz experimentally established the existence of electromagnetic waves. After its discovery, attempts were made to establish communication using electromagnetic waves, culminating in the creation of radio, and intensive research began in the field of radio engineering.

At the end of XIX - beginning of XX centuries. a new stage in the development of the theory of electricity began. Research on electrical discharges culminated in the discovery by J. J. Thomson of the discreteness of electric charges. In 1897 he measured the ratio of the electron's charge to its mass, and in 1898 he determined the absolute value of the electron's charge. H. Lorentz, relying on the discovery of Thomson and the conclusions of the molecular-kinetic theory, laid the foundations of the electronic theory of the structure of matter. In the classical electron theory, matter is considered as a collection of electrically charged particles whose motion is subject to the laws of classical mechanics. Maxwell's equations are obtained from the equations of electron theory by statistical averaging.

Attempts to apply the laws of classical electrodynamics to the study of electromagnetic processes in moving media ran into significant difficulties. In an effort to resolve them, A. Einstein came (1905) to the relativity of the theory. This theory finally refuted the idea of ​​the existence of an ether endowed with mechanical properties. After the creation of the theory of relativity, it became obvious that the laws of electrodynamics cannot be reduced to the laws of classical mechanics.

At small space-time intervals, the quantum properties of the electromagnetic field, which are not taken into account by the classical theory of electricity, become significant. The quantum theory of electromagnetic processes - quantum electrodynamics - was created in the 2nd quarter of the 20th century. The quantum theory of matter and field already goes beyond the doctrine of electricity, studies more fundamental problems concerning the laws of motion elementary particles and their buildings.

With the discovery of new facts and the creation of new theories, the significance of the classical doctrine of electricity did not decrease, only the limits of applicability of classical electrodynamics were determined. Within these limits, Maxwell's equations and the classical electron theory remain valid, being the foundation of the modern theory of electricity.

Classical electrodynamics forms the basis of most sections of electrical engineering, radio engineering, electronics and optics (with the exception of quantum electronics). With the help of her equations, a huge number of problems of a theoretical and applied nature were solved. In particular, numerous problems of plasma behavior in the laboratory and in space are solved using Maxwell's equations.

INTRODUCTION

Let's start our story with the words of Tesla himself, who shortly before his death wrote a wonderful essay on the history of electrical engineering "The Tale of Electricity": "Who really wants to remember all the greatness of our time, he must get acquainted with the history of the science of electricity."

For the first time, the phenomena now called electrical were noticed in ancient China, India, and later in ancient greece. The surviving legends say that the ancient Greek philosopher Thales of Miletus (640-550 BC) already knew the property of amber, rubbed with fur or wool, to attract scraps of paper, fluffs and other light bodies. From the Greek name for amber - "electron" - this phenomenon later received the name of electrification.

For many centuries, electrical phenomena were considered manifestations of divine power, until in the 17th century. scientists did not come close to the study of electricity. Pendant, Gilbert, Otto von Guericke, Mushenbreck, Franklin, Oersted, Arago, Lomonosov, Luigi Galvani, Alessandro Volta - that's far from full list electrical scientists. Special mention should be made of the activities of the remarkable scientist André Marie Ampère, who laid the foundation for the study dynamic action electric current and established a number of laws of electrodynamics.

The discoveries of Oersted, Arago, Ampère interested the brilliant English physicist Michael Faraday and prompted him to study the whole range of questions about the transformation of electrical and magnetic energy into mechanical energy. Another English physicist James Clerk (Clark) Maxwell in 1873 published a major two-volume work "Treatise on Electricity and Magnetism", which combined the concepts of electricity, magnetism and electromagnetic field. From that moment began the era of active use electrical energy in Everyday life.

1. ELECTRICITY

Electricity is a concept that expresses properties and phenomena due to the structure of physical bodies and processes, the essence of which is the movement and interaction of microscopic charged particles of matter (electrons, ions, molecules, their complexes, etc.).

Gilbert first discovered that the properties of electrification are inherent not only in amber, but also in diamond, sulfur, and resin. He also noticed that some bodies, such as metals, stones, bone, do not electrify, and he divided all bodies found in nature, electrified and non-electrified. Paying special attention to the first, he made experiments to study their properties.

In 1650, the famous German scientist, burgomaster of the city of Magdeburg, the inventor of the air pump, Otto von Guericke, built a special " electric car", representing a ball of sulfur the size of a child's head, mounted on an axis.

Figure 1 - Von Guericke's electric machine, improved by Van de Graaf

If, during the rotation of the ball, it was rubbed with the palms of the hands, it soon acquired the property of attracting and repelling light bodies. Over the course of several centuries, Guericke's machine was significantly improved by the Englishman Hawksby, the German scientists Bose, Winkler and others. Experiments with these machines led to a number of important discoveries:

· in 1707, the French physicist du Fay discovered the difference between the electricity obtained from the friction of a glass ball and that obtained from the friction of a tree resin twist;

· In 1729, the Englishmen Gray and Wheeler discovered the ability of some bodies to conduct electricity and for the first time pointed out that all bodies can be divided into conductors and non-conductors of electricity.

But much more important discovery was described in 1729 by Mushenbreck, a professor of mathematics and philosophy in the city of Leiden. He discovered that a glass jar, pasted on both sides with tin foil (steel sheets), was able to accumulate electricity. Charged to a certain potential (the concept of which appeared much later), this device could be discharged with a significant effect - a large spark that produced a strong crackle, like a lightning discharge, and had physiological actions when hands touch the lining of the jar. From the name of the city where the experiments were carried out, the device created by Mushenbreck was called the Leyden jar.

Figure 2 - Leiden jar. Parallel connection four cans

Studies of its properties were carried out in various countries and caused the emergence of many theories that tried to explain the discovered phenomenon of charge condensation. One of the theories of this phenomenon was given by the outstanding American scientist and public figure Benjamin Franklin, who pointed out the existence of positive and negative electricity. From the point of view of this theory, Franklin explained the process of charging and discharging a Leyden jar and proved that its plates can be arbitrarily electrified by electric charges of different signs.

Franklin, like the Russian scientists M. V. Lomonosov and G. Richman, paid much attention to the study of atmospheric electricity, lightning discharge (lightning). As you know, Richman died making an experiment on the study of lightning. In 1752, Benjamin Franklin invented the lightning rod. Lightning rod (more euphonious "lightning rod" is also used in everyday life) - a device installed on buildings and structures and serving to protect against lightning strikes. Consists of three interconnected parts:

In 1785, S. Coulomb discovered the basic law of electrostatics. Based on numerous experiments, Coulomb established the following law:

The force of interaction of stationary charges in vacuum is directly proportional to the product of charge modules and inversely proportional to the square of the distance between them - , :

In 1799, the first source of electric current was created - a galvanic cell and a battery of cells. Galvanic cell (chemical current source) - a device that allows you to convert energy chemical reaction in electrical work. According to the principle of operation, primary (one-time), secondary (batteries) and fuel cells are distinguished. The galvanic cell consists of an ion-conducting electrolyte and two dissimilar electrodes (half cells), the processes of oxidation and reduction in the galvanic cell are spatially separated. The positive pole of a galvanic cell is called cathode, negative - anode. The electrons exit the cell through the anode and travel in an external circuit to the cathode.

The works of Russian academicians Aepinus, Kraft and others revealed a number of very important properties of electric charge, but they all studied electricity in a stationary state or its instantaneous discharge, that is, the properties of static electricity. His movement manifested itself only in the form of a discharge. Nothing was yet known about electric current, that is, about the continuous movement of electricity.

One of the first to deeply investigate the properties of electric current in 1801-1802 was the St. Petersburg academician V.V. Petrov. The work of this outstanding scientist, who built the largest battery in the world in those years from 4200 copper and zinc circles, established the possibility of the practical use of electric current to heat conductors. In addition, Petrov observed the phenomenon of an electric discharge between the ends of slightly diluted coals both in air and in other gases and vacuum, which was called an electric arc. V. V. Petrov not only described the phenomenon he discovered, but also pointed out the possibility of using it for lighting or melting metals, and thereby for the first time expressed the idea of practical application electric current. From this moment, the history of electrical engineering as an independent branch of technology should begin.

Experiments with electric current attracted the attention of many scientists from different countries. In 1802, the Italian scientist Romagnosi discovered the deviation of a magnetic needle under the influence of an electric current flowing through a nearby conductor. At the end of 1819, this phenomenon was again observed by the Danish physicist Oersted, who in March 1820 published a pamphlet in Latin under the title "Experiments concerning the action of an electric conflict on a magnetic needle." In this work, an electric current was called an "electric conflict".

As soon as Arago demonstrated Oersted's experience at a meeting of the Paris Academy of Sciences, Ampère, repeating it, on September 18, 1820, exactly a week later, submitted a report on his research to the academy. At the next meeting, on September 25, Ampère finished reading a report in which he outlined the laws of the interaction of two currents flowing through parallel conductors. From that moment on, the academy listened weekly to Ampère's new reports on his experiments, which completed the discovery and formulation of the basic laws of electrodynamics.

One of the most important merits of Ampere was that he was the first to combine two previously separated phenomena - electricity and magnetism - into one theory of electromagnetism and proposed to consider them as the result of a single process of nature. This theory, met with great distrust by Ampère's contemporaries, was very progressive and played a huge role in the correct understanding of later discovered phenomena.

In 1827, the German scientist Georg Ohm discovered one of the fundamental laws of electricity, establishing the basic relationships between the current strength, voltage and resistance of the circuit through which the electric current flows, , ,

In 1847, Kirchhoff formulated the laws for the deployment of currents in complex circuits , , , :

Kirchhoff's first law

It is applied to nodes and is formulated as follows: the algebraic sum of the currents in the node is equal to zero. The signs are determined depending on whether the current is directed to the node or away from it (in any case, arbitrarily).

Kirchhoff's second law

Applies to circuits: in any circuit, the sum of the voltages on all elements and sections of the circuit included in this circuit is equal to zero. The direction of bypassing each contour can be chosen arbitrarily. Signs are determined depending on the coincidence of voltages with the direction of bypass.

The second formulation: in any closed circuit, the algebraic sum of voltages in all sections with resistances included in this circuit is equal to the algebraic sum of the EMF.

Generalization of Kirchhoff's laws

Let Y be the number of chain nodes, B the number of branches, K the number of circuits.

Figure 3 - Linear branched electrical circuit (U=3, V=5, K=6)

2. MAGNETISM (MAGNETS)

Magnetism- it is a form of interaction between moving electric charges carried out at a distance by means of a magnetic field.

A magnetic field is a special kind of matter, a specific feature of which is the action on a moving electric charge, current-carrying conductors, bodies with a magnetic moment, with a force depending on the charge velocity vector, the direction of the current strength in the conductor and on the direction magnetic moment body .

A permanent magnet is a product made of a hard magnetic material, an autonomous source of a constant magnetic field.
magnets [gr. magnetis, from Magnetis Lithos, a stone from Magnesia ( ancient city in Asia Minor)] are natural and artificial. A natural magnet is a piece of iron ore, which has the ability to attract small iron objects that are nearby.

Giant natural magnets are the Earth and other planets (Magnitosphere) as they have a magnetic field. Artificial magnets are objects and products that have received magnetic properties as a result of contact with a natural magnet or magnetized in a magnetic field. A permanent magnet is an artificial magnet.

In the simplest cases, a permanent magnet is a body (in the form of a horseshoe, strip, washer, rod, etc.) that has undergone appropriate heat treatment and is pre-magnetized to saturation.

Figure 4 - Types of magnets: a) horseshoe; b) strip; c) circular

A permanent magnet is usually included as an integral part in a magnetic system designed to form a magnetic field. The strength of the magnetic field generated by a permanent magnet can be either constant or adjustable.
Different parts of a permanent magnet attract iron objects in different ways. The ends of the magnet, where the attraction is maximum, are called the poles of the magnet, and the middle part, where the attraction is practically absent, is called the neutral zone of the magnet. Artificial magnets in the form of a strip or a horseshoe always have two poles at the ends of the strip and a neutral zone between them. It is possible to magnetize a piece of steel in such a way that it will have 4, 6 or more poles separated by neutral zones, while the number of poles always remains even. It is impossible to get a magnet with one pole. The ratio between the dimensions of the pole regions and the neutral zone of a magnet depends on its shape.

A solitary magnet in the form of a long and thin rod is called a magnetic needle. The end of a pointed or suspended magnetic needle - simple compass, indicates the geographical north of the Earth, and is called the north pole (N) of the magnet, the opposite pole of the magnet, points to the south, and is called the south pole (S).
The areas of application of permanent magnets are very diverse. They are used in electric motors, in automation, robotics, for magnetic couplings of magnetic bearings, in the watch industry, in household appliances, as autonomous sources of a constant magnetic field in electrical engineering and radio engineering.

Magnetic circuits, including permanent magnets, must be open, i.e., have an air gap. If a permanent magnet is made in the form of an annular core, then it practically does not give off energy to the external space, since almost all magnetic lines of force locked up inside it. In this case, the magnetic field outside the core is practically absent. To use the magnetic energy of permanent magnets, it is necessary to create an air gap of a certain size in a closed magnetic circuit.

When a permanent magnet is used to create magnetic flux in an air gap, such as between the poles of a horseshoe magnet, the air gap reduces the induction (and magnetization) of the permanent magnet.

3. ELECTROMAGNETISM

The electromagnetic interaction is one of the four fundamental interactions. Electromagnetic interaction exists between particles that have an electric charge. From the modern point of view, the electromagnetic interaction between charged particles is not carried out directly, but only through the electromagnetic field.

From the point of view of quantum field theory, the electromagnetic interaction is carried by a massless boson - a photon (a particle that can be represented as a quantum excitation of an electromagnetic field). The photon itself does not have an electric charge, which means it cannot directly interact with other photons.

Of the fundamental particles, particles with an electric charge also participate in electromagnetic interaction: quarks, an electron, a muon and a tau particle (from fermions), as well as charged gauge bosons.

The electromagnetic interaction differs from the weak and strong interactions by its long-range character—the force of interaction between two charges falls off only as the second power of the distance (see: Coulomb's law). According to the same law, the gravitational interaction decreases with distance.

The electromagnetic interaction of charged particles is much stronger than the gravitational one, and the only reason why the electromagnetic interaction does not manifest itself with great force on a cosmic scale is the electrical neutrality of matter, that is, the presence in each region of the Universe with a high degree of accuracy of equal amounts of positive and negative charges.

Electromagnetic field- this is a special form of matter, through which the interaction between charged particles is carried out. Represents interrelated variables electric field and magnetic field. The mutual connection of the electric E and magnetic H fields lies in the fact that any change in one of them leads to the appearance of the other: an alternating electric field generated by rapidly moving charges (source) excites an alternating magnetic field in adjacent regions of space, which, in turn, excites an alternating electric field in the adjacent regions of space, etc. Thus, the electromagnetic field propagates from point to point in space in the form of electromagnetic waves running from the source. Due to the finiteness of the propagation velocity, the electromagnetic field can exist autonomously from the source that generated it and does not disappear with the elimination of the source (for example, radio waves do not disappear with the termination of the current in the antenna that emitted them).

The electromagnetic field in vacuum is described by the electric field strength E and the magnetic induction B. The electromagnetic field in the medium is additionally characterized by two auxiliary quantities: the magnetic field strength H and the electric induction D. The connection of the electromagnetic field components with charges and currents is described by Maxwell's equations.

Electromagnetic waves are electromagnetic oscillations propagating in space with a finite speed depending on the properties of the medium (Figure 5).

Figure 5 - Electromagnetic waves

The existence of electromagnetic waves was predicted by the English physicist M. Faraday in 1832. Another English scientist, J. Maxwell, in 1865 theoretically showed that electromagnetic oscillations do not remain localized in space, but propagate in all directions from the source. Maxwell's theory made it possible to approach the description of radio waves, optical radiation, X-ray radiation, and gamma radiation in a unified way. It turned out that all these types of radiation are electromagnetic waves with different wavelengths λ, that is, they are related in nature. Each of them has its specific place in a single scale of electromagnetic waves (Figure 6).

Figure 6 - Scale of electromagnetic waves

Propagating in media, electromagnetic waves, like any other waves, can experience refraction and reflection at the interface between media, dispersion, absorption, interference; when propagating in inhomogeneous media, wave diffraction, wave scattering, and other phenomena are observed.

Electromagnetic waves of different wavelength ranges are characterized by different ways of excitation and registration, interact differently with matter. The processes of emission and absorption of electromagnetic waves from the longest to IR radiation are quite fully described by the relations of classical electrodynamics.

In the ranges of shorter wavelengths, especially in the ranges of x-rays and γ-rays, processes of a quantum nature dominate and can only be described within the framework of quantum electrodynamics based on the concept of the discreteness of these processes.

Electromagnetic waves are widely used in radio communications, radar, television, medicine, biology, physics, astronomy, and other fields of science and technology.

The discoveries of Oersted, Arago, Ampère interested the brilliant English physicist Michael Faraday and prompted him to study the whole range of questions about the transformation of electrical and magnetic energy into mechanical energy. In 1821, he found another solution to the problem of converting electrical and magnetic energy into mechanical energy and demonstrated his device, in which he obtained the phenomenon of continuous electromagnetic rotation. On the same day, Faraday wrote in his work diary the inverse problem: "Turn magnetism into electricity." It took more than ten years to solve it and find a way to obtain electrical energy from magnetic and mechanical. Only at the end of 1831, Faraday announced his discovery of a phenomenon, which was later called electromagnetic induction and which forms the basis of all modern electric power industry.

4. ELECTRIC MACHINES

The study of Faraday and the work of the Russian academician E. X. Lenz, who formulated the law by which it was possible to determine the direction of the electric current resulting from electromagnetic induction, made it possible to create the first electromagnetic generators and electric motors.

Initially, electric generators and electric motors developed independently of each other, as two completely different machines. The first inventor of an electric generator based on the principle of electromagnetic induction wished to remain anonymous. It happened like this. Shortly after the publication of Faraday's report to the Royal Society, which outlined the discovery of electromagnetic induction, the scientist found in his mailbox a letter signed with the initials R. M. It contained a description of the world's first synchronous generator and accompanying drawing. Faraday, having carefully examined this project, sent a letter to R. M. and a drawing to the same journal in which his report was published at one time, hoping that the unknown inventor, following the journal, would see not only his project published, but also the accompanying letter from Faraday, which highly appreciates the invention of R. M-,,.

Indeed, after almost six months, R. M. sent additional explanations and a description of the design of the electric generator proposed by him, but this time also wished to remain anonymous. The name of the true creator of the first electromagnetic generator has remained hidden under the initials, and humanity still, despite the thorough searches of historians of electrical engineering, remains in the dark to whom it owes one of the most important inventions. The R. M. machine did not have a device for rectifying the current and was the first generator alternating current. But this current, it seemed, could not be used for arc lighting, electrolysis, telegraphy, which were already firmly established in life. It was necessary, according to the designers of that time, to create a machine in which it would be possible to obtain a current that was constant in direction and magnitude.

Almost simultaneously with R. M., the Pixie brothers and the professor of physics at the University of London and a member of the Royal Society V. Ricci were engaged in the design of generators. The machines they created had a special device for rectifying alternating current into direct current - the so-called collector. Further development of generator designs direct current proceeded at an unusually fast pace. In less than forty years, the dynamo has almost completely taken the form of the modern DC generator. True, the winding of these dynamos was unevenly distributed around the circumference, which worsened the operation of such generators - the voltage in them either increased or decreased, causing unpleasant shocks.

In 1870, Zenobaeus Gramm proposed a special, so-called ring winding of the dynamo armature. The uniform distribution of the armature winding made it possible to obtain a completely uniform voltage in the generator and the same rotation of the engine, which significantly improved the properties of electrical machines. In essence, this invention repeated what had already been created and described in 1860 by the Italian physicist Pachinnoti, but went unnoticed and remained unknown to 3. Gram. Machines with a ring armature became especially widespread after the reversibility of Gramm's electrical machines was discovered at the Vienna World Exhibition in 1873: the same machine, when the armature rotated, gave electric current, when current flowed through the armature, it rotated and could be used as electric motor.

From that time on, a rapid growth in the use of electric motors and an ever-expanding consumption of electricity began, which was greatly facilitated by the invention of P. N. Yablochkov, a method of lighting using the so-called "Yablochkov candle" - an arc electric lamp with a parallel arrangement of coals.

The simplicity and convenience of "Yablochkov's candles", which replaced expensive, complex and bulky arc lamps with regulators for the continuous convergence of burning coals, caused their widespread distribution, and soon "Yablochkov's light", "Russian" or "northern" light, illuminated the boulevards of Paris, embankments Thames, avenues of the capital of Russia and even the ancient cities of Cambodia. This was a real triumph for the Russian inventor.

But to supply these candles with electricity, it was necessary to create special electric generators that provide not direct, but alternating current, that is, current, although not often, but continuously changing its magnitude and direction. This was necessary because the coals connected to different poles of the DC generator burned unevenly - the anode connected to the positive burned out twice as fast as the cathode. Alternating current alternately turned the anode into a cathode and thus ensured uniform combustion of coals. Especially for powering "Yablochkov's candles", an alternating current generator was created by P. N. Yablochkov himself, and then improved by French engineers Lontin and Gram. However, an AC motor has not yet been thought of.

At the same time, for separate power supply of individual candles from an alternator, the inventor created a special device - an induction coil (transformer), which made it possible to change the voltage in any branch of the circuit in accordance with the number of connected candles. Soon, the growing demand for electricity and the possibility of obtaining it in large quantities came into conflict with the limited possibilities of transmitting it over a distance. The low voltage (100-120 volts) of direct current used at that time and its transmission through wires of a relatively small cross section caused huge losses in transmission lines. Since the end of the 70s of the last century, the main problem, on the successful solution of which the whole future of electrical engineering depended, was the problem of transmitting electricity over long distances without large losses.

First theoretical background the possibility of transmitting any amount of electricity at any distance over wires of relatively small diameter without significant losses by increasing the voltage was given by D. A. Lachinov, professor of physics at the St. Petersburg Forestry Institute, in July 1880. Following this, the French physicist and electrical engineer Marcel Despres in 1882 at the Munich Electrical Exhibition carried out the transmission of electricity of several horsepower over a distance of 57 kilometers with an efficiency of 38 percent.

Later, Despres made a number of experiments, carrying out the transmission of electricity over a distance of a hundred kilometers and bringing the transmission power to several hundred kilowatts. A further increase in distance required a significant increase in voltage. Deprez brought it up to 6 thousand volts and made sure that the insulation of the plates in the collector of generators and DC motors did not allow a higher voltage to be reached.

Despite all these difficulties, at the beginning of the 80s, the development of industry and the concentration of production more and more urgently demanded the creation of a new engine, more advanced than the widespread steam engine. It was already clear that it was profitable to build power plants near coal deposits or on rivers with a large drop in water, while building factories closer to sources of raw materials. This often required the transmission of huge amounts of electricity to the objects of its consumption over long distances. Such a transmission would be expedient only when applying a voltage of tens of thousands of volts. But it was impossible to obtain such a voltage in DC generators. Alternating current and a transformer came to the rescue: using them, they began to produce low-voltage alternating current, then increase it to any required value, transmit it over a distance high voltage, and at the place of consumption, again reduce to the required level and use in pantographs.

There were no AC motors yet. After all, already in the early 80s, electricity was consumed mainly for power needs. DC motors for driving the most various machines used more and more frequently. To create an electric motor that could run on alternating current has become the main task of electrical engineering. In search of new paths, it is always necessary to look back. Was there anything in the history of electrical engineering that could suggest the way to the creation of an alternating current motor? Searches in the past have been successful. They remembered: back in 1824, Arago demonstrated an experience that marked the beginning of many fruitful studies. It is a question of demonstration of "magnetism of rotation". A copper (not magnetic) disk was entrained by a rotating magnet.

The idea arose, is it possible, by replacing the disk with winding turns, and the rotating magnet with a rotating magnetic field, to create an alternating current electric motor? Probably, it is possible, but how to get the rotation of the magnetic field?

During these years, many various ways AC applications. A conscientious historian of electrical engineering will have to name the various physicists and engineers who tried to create AC motors in the mid-80s. He will not forget to recall the experiments of Bailey (1879), Marcel Despres (1883), Bradley (1887), the works of Wenstrom, Haselwander and many others. The proposals were undoubtedly very interesting, but none of them could satisfy the industry: their electric motors were either bulky and uneconomical, or complex and unreliable. The very principle of building simple economical and reliable AC motors has not yet been found.

It was during this period that Nikola Tesla began, as we already know, the search for a solution to this problem. He went his own way, by reflecting on the essence of Arago's experience, and proposed a radical solution to the problem that immediately turned out to be acceptable for practical purposes. Back in Budapest in the spring of 1882, Tesla clearly imagined that if the windings of the magnetic poles of an electric motor were somehow powered by two different alternating currents, differing from each other only in phase shift, then the alternation of these currents would cause the alternating formation of the north and south poles or rotation magnetic field. The rotating magnetic field should also entrain the winding of the rotor of the machine.

Having built a special source of two-phase current (two-phase generator) and the same two-phase electric motor, Tesla realized his idea. And although his machines were structurally very imperfect, the principle of a rotating magnetic field, applied in the very first Tesla models, turned out to be correct.

Having considered all possible cases of phase shift, Tesla settled on a shift of 90 °, that is, on a two-phase current. This was quite logical - before creating electric motors with a large number of phases, one should start with a two-phase current. But another phase shift could also be applied: by 120° ( three-phase current). Without analyzing theoretically and comprehending all possible cases, without even comparing them with each other (this is Tesla's big mistake), he focused all his attention on two-phase current, creating two-phase generators and electric motors, and only briefly mentioned polyphase currents in his patent applications. and the possibility of their application.

But Tesla was not the only scientist who remembered Arago's experience and found a solution to an important problem. In the same years, research in the field of alternating currents was carried out by the Italian physicist Galileo Ferraris, the representative of Italy at many international congresses of electricians (1881 and 1882 in Paris, 1883 in Vienna and others). Preparing lectures on optics, he came to the idea of ​​the possibility of setting up an experiment demonstrating the properties of light waves. To do this, Ferraris reinforced a copper cylinder on a thin thread, which was acted upon by two magnetic fields shifted at an angle of 90 °. When the current is turned on in the coils, which alternately create magnetic fields in one or the other of them, the cylinder turns under the influence of these fields and twists the thread, as a result of which it rises by a certain amount. This device perfectly simulated the phenomenon known as the polarization of light.

Ferraris did not intend to use his model for any electrical purposes. It was only a lecture instrument, the ingenuity of which lay in the skillful application of the electrodynamic phenomenon for demonstrations in the field of optics.

Ferraris was not limited to this model. In the second, more advanced model, he managed to achieve cylinder rotation at a speed of up to 900 revolutions per minute. But beyond certain limits, no matter how much the strength of the current that created the magnetic fields increased in the circuit (in other words, no matter how much the power expended increased), it was not possible to achieve an increase in the number of revolutions. Calculations showed that the power of the second model did not exceed 3 watts.

Undoubtedly, Ferraris, being not only an optician, but also an electrician, could not but understand the significance of his experiments. However, by his own admission, it never occurred to him to apply this principle to the creation of an alternating current electric motor. The most he envisioned was to use it to measure the strength of current, and even began to design such a device.

March 18, 1888 at the Turin Academy of Sciences, Ferraris made a report "Electrodynamic rotation produced by alternating currents." In it, he spoke about his experiments and tried to prove that it was impossible to obtain an efficiency of more than 50 percent in such a device. Ferraris was sincerely convinced that by proving the inexpediency of using alternating magnetic fields for practical purposes, he was doing a great service to science. Ferraris' report was ahead of Nikola Tesla's report at the American Institute of Electrical Engineers. But the application filed for a patent back in October 1887 testifies to Tesla's undoubted priority over Ferraris. As for the publication, Ferraris's article, available for reading to all electricians of the world, was published only in June 1888, that is, after Tesla's widely known report.

To Ferraris' assertion that he had begun work on the study of a rotating magnetic field in 1885, Tesla had every reason to object that he had dealt with this problem back in Graz, found a solution in 1882, and in 1884 in Strasbourg demonstrated a working model of his engine. But, of course, it's not just a matter of priority. Undoubtedly, both scientists made the same discovery independently of each other: Ferraris could not have known about Tesla's patent application, just as the latter could not have known about the work of the Italian physicist.

It is much more important that G. Ferraris, having discovered the phenomenon of a rotating magnetic field and having built his model with a power of 3 watts, did not think about their practical use. Moreover, if the erroneous conclusion of Ferraris about the inexpediency of using alternating multiphase currents had been accepted, then humanity would have been directed along the wrong path for several more years and deprived of the possibility of widespread use of electricity in the most various industries production and life. The merit of Nikola Tesla lies in the fact that, despite many obstacles and a skeptical attitude towards alternating current, he practically proved the feasibility of using polyphase current. The first two-phase current motors he created, although they had a number of shortcomings, attracted the attention of electrical engineers around the world and aroused interest in his proposals.

However, an article by Galileo Ferraris in the journal "Atti di Turino" played a huge role in the development of electrical engineering. It was reprinted by a major English magazine, and the issue with this article fell into the hands of another scientist, now deservedly recognized as the creator of modern three-phase electrical engineering.

5. Tesla transformer

Tesla transformers are known for their various designs, from the simplest ones with a spark gap to modern circuits with high-frequency master oscillators for its primary winding, made both on semiconductor and on lamp circuits.

Scheme of the simplest Tesla transformer:

In its elementary form, the Tesla transformer consists of two coils, primary and secondary, and a harness consisting of a spark gap (breaker, the English version of Spark Gap is often found), a capacitor, a toroid (not always used) and a terminal (shown as an “output” in the diagram) .

Figure 7 - The simplest circuit Tesla transformer

Figure 8 - Tesla transformer in action

The primary coil is built from 5-30 (for VTTC - Tesla coil on a lamp - the number of turns can be up to 60) turns of large diameter wire or copper tube, and the secondary of many turns of wire of smaller diameter. The primary coil can be flat (horizontal), conical or cylindrical (vertical). Unlike many other transformers, there is no ferromagnetic core here. Thus, the mutual inductance between the two coils is much less than conventional transformers with a ferromagnetic core. This transformer also has practically no magnetic hysteresis, the phenomenon of delay in the change in magnetic induction relative to the change in current, and other disadvantages introduced by the presence of a ferromagnet in the field of the transformer.

The primary coil, together with the capacitor, forms an oscillatory circuit, which includes a nonlinear element - a spark gap (spark gap). The arrester, in the simplest case, is an ordinary gas one; usually made of massive electrodes (sometimes with radiators), which is made for greater wear resistance when high currents flow through an electric arc between them.

The secondary coil also forms an oscillatory circuit, where the capacitive coupling between the toroid, the terminal device, the turns of the coil itself and other electrically conductive elements of the circuit with the Earth performs the role of a capacitor. The terminal device (terminal) can be made in the form of a disk, a sharpened pin or a sphere. The terminal is designed to produce long, predictable sparks. The geometry and relative position of the parts of the Tesla transformer greatly affects its performance, which is similar to the problem of designing any high-voltage and high-frequency devices.

CONCLUSION

Things that use electricity that have become familiar in our daily life are the fruits of the scientific and technical thought of many generations of scientists. Often the understanding of the practical value and significance of the discovered phenomena came late or came with the next generation of scientists.

However, it should be noted that it was the development of electrical engineering that contributed to the acceleration of technological progress. The creation and development of electric machines of direct and alternating current made it possible to design flexible control systems, which could not be implemented on engines using the energy of gas and liquid. The development of microprocessor technology has made it possible to create powerful computers that participate in the experiments of theoretical physicists who discover the secrets of the universe (LHC at CERN).

It is my deep conviction that there are still quite a few mysteries, mysteries and great discoveries left in the field of electrical engineering.

BIBLIOGRAPHY

1. V.Z. Ozernikov “Non-random accidents. Stories about great discoveries and outstanding scientists"

2. L.S. Zhdanov, V.A. Marandzhyan “Physics course”

3. Schoolchildren's handbook, edited by A. Barashkov

4. M.I. Bludov "Conversations on Physics"

5. M.I. Yakovleva " Physiological mechanisms action of electromagnetic fields"

6. A.A. Borovoy, E.B. Finkelstein, A.N. Kherubimov "Laws of electromagnetism"

7. I.E. Irodov Electromagnetism. Basic laws. Physics course.

8. V.P. Safronov, B.B. Konkin, V.A.Vagan "Physics: A Short Course"

A branch of physics that studies electrical phenomena: the interaction between charged bodies, the phenomena of polarization and the passage of an electric current.
The connection between electrical and magnetic phenomena is studied by electromagnetism. Electrodynamics, including electricity and magnetism, also studies electromagnetic waves.
Applied sciences, such as electrical engineering, electrochemistry, etc., base their knowledge on electricity.
The ancient Greek philosopher Thales of Miletus was one of the first researchers of electricity. Electrical phenomena were known in antiquity to the ancient Greeks, Phoenicians, and the inhabitants of Mesopotamia. The fact that, when rubbed, amber acquires the ability to attract light objects to itself, was described in the 600s BC Thales of Miletus. Thales, however, did not distinguish electricity from magnetism, considering this to be one phenomenon, only amber acquires such a strange property during friction, and in magnetite it is constant.
A new step in the study of electrical phenomena was made in 1600 by the English physician William Gilbert. After conducting research on electrical and magnetic phenomena, he published a book in which he concluded that the properties of a permanent magnet and the ability of rubbed amber to attract objects are definitely different phenomena. Gilbert began to use the Latin word electricus Burshtin-like, to describe such a property. In his book, Gilbert also came to the conclusion that the Earth is a magnet, and that is why the compass needle points to the pole.
Permanent magnet the simplest example magnetic dipole. In the middle of the 17th century, Otto von Guericke invented the electrostatic generator.
Stephen Gray's experiments showed that electricity could be transmitted up to 800 feet with wetted filament conductors, if ground contact was avoided and insulation was used. Thus began research on currents and laid the foundations for the separation of materials into conductors and dielectrics.
Charles du Fou opened two various types electricity, calling them "glassy" and "resinous" now they are called positive and negative charges, demonstrating that like charges repel and unlike charges attract. Du Fou also divided substances into conductors and insulators, calling them "electrics" and "non-electrics".
The experiments of Benjamin Franklin, carried out in 1752, demonstrated that lightning is electrical in nature.
Benjamin Franklin USA, politician and inventor. Conducted research on electricity in the 18th century. In 1791, Luigi Galvani published the discoveries of bioelectrics. In 1800, Alessandro Volta built the first battery of voltaic pillars. new type The current source was much more reliable than the electrostatic generators that had been used previously. In 1820, André Marie Ampère discovered the connection between electricity and magnetism. In 1821, Michael Faraday invented the electric motor, and in 1827 Georg Ohm established a mathematical law describing the current in electrical circuit.
Thomas Edison It is difficult to enumerate all the scientific discoveries in the field of electrical phenomena in the first half of the 19th century. The discovery of electromagnetic induction by Faraday in 1831 paved the way for the production and use of electrical energy on a large scale, and the end of the 19th century was the era of numerous inventions in the field of electrical engineering. By the end of the century, through the efforts of such eminent scientists as Nikola Tesla, Thomas Alva Edison, Werner von Siemens, Lord Kelvin, Galileo Ferraris and many others, electricity turned from scientific interest into the leading force of the second industrial revolution.
An electric arc provides a visual demonstration of electric current Basic Elements of an Electrical Circuit Modern physics considers the electromagnetic interaction to be one of the fundamental interactions. Electric charge is a property of elementary particles, among which the most important, given their stability, are the electron and proton. All substances are composed of atoms, in the center of which there is a positively charged nucleus, and around the nucleus there are negatively charged electrons. Most atoms in the world around them have a neutral number of electrons equal to the number of protons, but mobile electrons can leave an atom, forming positive ions, or join a neutral atom, forming negative ions. If in any physical body the number of electrons differs from the number of protons, then such a body receives a macroscopic electric charge. This process is called electrification.
Like charges repel, and unlike charges attract. Numerically, the interaction between charges is described by the Coulomb law.
If charges are placed in a continuous medium, then the interaction between them changes due to a phenomenon called dielectric polarization. Dielectric polarization occurs due to the displacement of electrons relative to the nuclei of atoms in the outer electric field or due to the rotation of molecules with their own dipole moment. As a result, the force acting on a charge from other charges is determined not only by the magnitude of these charges and their location, but also by the reduced dipole moments of the atoms and molecules of the medium. At small electric fields compared to intraatomic fields, the ability of a substance to polarize is described by permittivity.
Under the action of the Coulomb force, charged particles move, forming an electric current. An electric current creates a magnetic field by which it can be registered. Another consequence of the passage of an electric current through a substance is the release of heat.
Dependences on the ability to conduct an electric current of a substance can be divided into conductors and dielectrics.
Since the end of the 19th century, electrical phenomena have played an increasingly important role in production and everyday life. Electricity is at the center of our culture, from lighting and home appliances to powerful electric motors used in manufacturing.
Production

Read more in the article Energy

Mainly intended for use in production and everyday life, electricity is generated by power plants, where mechanical energy rotation of steam turbines is converted into electricity by electric generators. The heat needed to heat the steam that turns the turbines comes mainly from fossil fuels. In addition to thermal power plants, a significant part of the electricity is generated by nuclear power plants and hydroelectric power plants. In the latter case, renewable energy sources are used. Other renewable energy sources are wind energy, which is used by increasingly popular wind farms in the modern era. Direct use of solar energy is possible thanks to solar cells.
The energy produced by power plants is distributed through the electrical network in people's homes, factories and factories.
In addition to the production and distribution of electrical energy over the network, such sources of electrical energy as electrochemical batteries and accumulators are also widely used, which make it possible to obtain electric current. small voltage necessary for the operation of portable electronic devices.
Usage
In the 1870s, the incandescent lamp appeared, which became the first household appliance that required electrical network into every human home and institution. Even before its appearance, electricity was used by the telegraph and telephone as important communication devices. Important household electrical appliances include: radio, TV, record player, washing machine, refrigerator, air conditioner, heater and many others. Many of these appliances use an electric motor invented by Michael Faraday. With the development of electronics, computers also appeared in human homes.
Manufacturing also makes extensive use of powerful electric motors, but electrical phenomena are also applied to electroforming, metal smelting, welding, and many other ways.

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Where did it start? I think that hardly anyone will give an exact, exhaustive answer to this question. But still, let's try to figure it out.

Phenomena related to electricity were seen in ancient China, India and ancient Greece several centuries before the beginning of our era. Near 600 BC., as the surviving legends say, the ancient Greek philosopher Thales of Miletus knew the property of amber rubbed on wool to attract light objects. By the way, the word "electron" the ancient Greeks called amber. The word "electricity" also came from him. But the Greeks only observed the phenomena of electricity, but could not explain.

Only in 1600 the court physician of the English Queen Elizabeth William Gilbert, using his electroscope, proved that not only rubbed amber, but also other minerals have the ability to attract light bodies: diamond, sapphire, opal, amethyst, etc. In the same year, he publishes the work “On the Magnet and magnetic bodies”, where he outlined a whole body of knowledge about magnetism and electricity.

In 1650 German scientist and part-time burgomaster of Magdeburg Otto von Guericke creates the first “electric machine”. It was a ball cast from sulfur, during rotation and rubbing of which, light bodies were attracted and repelled. Subsequently, his car was improved by German and French scientists.

In 1729 Englishman Stephen Gray discovered the ability of certain substances to conduct electricity. He, in fact, first introduced the concept of conductors and non-conductors of electricity.

In 1733 French physicist Charles Francois Dufay discovered two types of electricity: "tar" and "glass". One appears in amber, silk, paper; the second - in glass, precious stones, wool.

In 1745 Dutch physicist and mathematician at the University of Leiden Pieter van Muschenbroek discovered that a glass jar covered with tin foil can store electricity. Muschenbroek called it the Leyden jar. It was essentially the first electrical capacitor.

In 1747 Physicist Jean Antoine Nollet, a member of the Paris Academy of Sciences, invented the electroscope, the first instrument for assessing electric potential. He also formulated the theory of the action of electricity on living organisms and revealed the property of electricity to “drain” faster from sharper bodies.

In 1747-1753. American scientist and statesman Benjamin Franklin made a number of studies and related discoveries. He introduced the concept of two charged states, which is still used: «+» and «-» . He explained the action of the Leyden jar, establishing the decisive role of the dielectric between the conductive plates. Established the electrical nature of lightning. He proposed the idea of ​​a lightning rod, having established that metal points connected to the ground remove electric charges from charged bodies. He put forward the idea of ​​an electric motor. He was the first to use an electric spark to ignite gunpowder.

In 1785-1789. French physicist Charles Augustin Coulomb publishes a series of papers on the interaction of electric charges and magnetic poles. Carries out the proof of the location of electric charges on the surface of the conductor. Introduces the concepts of magnetic moment and polarization of charges.

In 1791 The Italian physician and anatomist Luigi Galvani discovered the occurrence of electricity when two dissimilar metals come into contact with a living organism. The effect he discovered underlies modern electrocardiographs.

In 1795 another Italian scientist Alessandro Volta, investigating the effect discovered by his predecessor, proved that an electric current occurs between a pair of dissimilar metals separated by a special conductive liquid.

In 1801 Russian scientist Vasily Vladimirovich Petrov established the possibility of practical use of electric current for heating conductors, observed the phenomenon of an electric arc in vacuum and various gases. He put forward the idea of ​​using current for lighting and melting metals.

In 1820 Danish physicist Hans Christian Oersted established the connection between electricity and magnetism, which laid the foundation for the formation of modern electrical engineering. In the same year, the French physicist André Marie Ampère formulated a rule for determining the direction of action of an electric current on a magnetic field. He was the first to combine electricity and magnetism and formulated the laws of interaction between electric and magnetic fields.

In 1827 German scientist Georg Simon Ohm discovered his law (Ohm's law) - one of the fundamental laws of electricity, establishing the relationship between current and voltage.

In 1831 English physicist Michael Faraday discovered the phenomenon of electromagnetic induction, which leads to the formation of a new industry - electrical engineering.

In 1847 German physicist Gustav Robert Kirchhoff formulated the laws for currents and voltages in electrical circuits.

The end of the 19th - beginning of the 20th centuries was full of discoveries related to electricity. One discovery spawned a whole chain of discoveries over several decades. Electricity from the subject of research began to turn into an object of consumption. It began to be widely introduced into various areas of production. Electric motors, generators, telephone, telegraph, radio were invented and created. The introduction of electricity into medicine begins.

In 1878 the streets of Paris were illuminated by the arc lamps of Pavel Nikolaevich Yablochkov. The first power plants appear. Not so long ago, seeming something incredible and fantastic, electricity is becoming a familiar and indispensable assistant to mankind.

About the history of electricity, briefly. Electricity is a branch of physics that talks about the properties and phenomena associated with the interaction of charged particles.

The discoveries made in this area of ​​the science of physics have radically influenced our lives. Therefore, one should never forget how this science began. The history of electricity dates back to ancient times. About the history of electricity, briefly.

The electric charge was first discovered by Thales of Miletus as early as 600 BC. e. He noticed that amber, worn on a piece of wool, acquires amazing properties to attract light non-electrified objects (fluff and pieces of paper). The term "electricity" was first introduced by the English scientist Tudor Gilbert in his book On Magnetic Properties, Magnetic Bodies, and the Great Magnet - the Earth. In his book, he proved that not only amber, but also other substances have the property of being electrified. And in the middle of the 17th century, the well-known scientist Otto von Guericke created an electrostatic machine in which he discovered the property of charged objects to repel each other. So the basic concepts in the electricity section began to appear. On the history of electricity.

Already in 1729, the French physicist Charles Dufay established the existence of two types of charges. He called such charges “glassy” and “resinous”, but soon, the German scientist Georg Lichtenberg introduced the concept of negatively and positively charged charges. And in 1745 the first ever electrical capacitor- the so-called Leyden bank.

But the opportunity to formulate the basic concepts and discoveries in the science of electricity was possible only when quantitative research appeared. Then began the time of discovery of the basic laws of electricity. The law of interaction of electronic charges was discovered in 1785 by the French scientist Charles Coulomb using the system of torsion balances he created.

Almost at the same time, in 1800, the Italian experimenter Volt invented the first direct current source in human life - an elementary galvanic cell. The great discoveries associated with the work of Joule, Ohm and Lenz, studying the manifestation of electric current in a circuit, became known. Faraday in 1831 and 1834 discovers electromagnetic induction and the famous laws of electrolysis.

Thus, as early as the 17th century, the electrical concept of matter began to take shape, according to which all physical bodies without exception are peculiar complexes of interacting particles. Therefore, in the future, many physical properties bodies are determined by the laws that were formulated in ancient times. The science of electricity does not stand still and every year there are more and more new discoveries in this field of science. On our website about electricity, you will always be up to date with all the new research on the history of electricity.