Life and work of Michael Faraday. Biography and discoveries of Michael Faraday. Interesting facts of Michael Faraday

Faraday, Michael

English physicist Michael Faraday was born on the outskirts of London in the family of a blacksmith. After graduating from elementary school, from the age of twelve he worked as a newspaper peddler, and in 1804 he was apprenticed to the bookbinder Ribot, a French emigrant who in every possible way encouraged Faraday's passionate desire for self-education. By reading and attending public lectures, the young Faraday sought to replenish his knowledge, and he was attracted mainly by the natural sciences - chemistry and physics. In 1813, one of the customers presented Faraday with invitation cards to lectures by Humphrey Davy at the Royal Institute, which played a decisive role in the fate of the young man. By writing to Davy, Faraday, with his help, received a position as a laboratory assistant at the Royal Institute.

In 1813-1815, while traveling with Davy in Europe, Faraday visited the laboratories of France and Italy. After returning to England, Faraday's scientific activity proceeded within the walls of the Royal Institute, where he first helped Davy in chemical experiments, and then began independent research. Faraday carried out the liquefaction of chlorine and some other gases, received benzene. In 1821, for the first time, he observed the rotation of a magnet around a current-carrying conductor and a current-carrying conductor around a magnet, and created the first model of an electric motor. Over the next 10 years, Faraday studied the relationship between electrical and magnetic phenomena. His research culminated in the discovery in 1831 of the phenomenon of electromagnetic induction. Faraday studied this phenomenon in detail, deduced its basic law, found out the dependence of the induction current on the magnetic properties of the medium, studied the phenomenon of self-induction and extra currents of closing and opening. The discovery of the phenomenon of electromagnetic induction immediately acquired great scientific and practical significance; this phenomenon underlies, for example, the operation of all alternating and direct current generators.

The desire to reveal the nature of electric current led Faraday to experiments on the passage of current through solutions of acids, salts and alkalis. The result of these studies was the discovery in 1833 of the laws of electrolysis (Faraday's laws). In 1845, Faraday discovered the phenomenon of rotation of the plane of polarization of light in a magnetic field (the Faraday effect). In the same year he discovered diamagnetism, in 1847 - paramagnetism. Faraday introduced a number of concepts into science - cathode, anode, ions, electrolysis, electrodes; in 1833 he invented the voltmeter. Using a huge experimental material, Faraday proved the identity of the then known "types" of electricity: "animal", "magnetic", thermoelectricity, galvanic electricity, etc.

In 1840, even before the discovery of the law of conservation of energy, Faraday expressed the idea of ​​the unity of the "forces" of nature (different types of energy) and their mutual transformation. He introduced ideas about lines of force, which he considered physically existing. Faraday's ideas about electric and magnetic fields had a great influence on the development of all physics. In 1832, Faraday suggested that the propagation of electromagnetic interactions is a wave process that occurs at a finite speed; in 1845 he first used the term "magnetic field".

In 1824, despite the opposition of Davy, who claimed the discoveries of his assistant, Faraday was elected a member of the Royal Society, and in 1825 became director of the laboratory at the Royal Institute. From 1833 to 1862 Faraday was a professor of chemistry at the Royal Institute. Faraday's public lectures were very popular; his popular science book The History of the Candle became widely known.

Faraday's discoveries won the widest recognition throughout the scientific world; laws, phenomena, units of physical quantities, etc. were subsequently named after him. The Russian physicist A. G. Stoletov described the importance of Faraday in the development of science as follows: “Never since the time of Galileo has the world seen so many amazing and diverse discoveries that came out of one head.” In honor of Michael Faraday, the British Chemical Society established the Faraday Medal, one of the most honored scientific awards.

The discoveries in physics of the English scientist, the founder of the theory of the electromagnetic field, influenced the development of science.

Michael Faraday invented what?

The scientist devoted a lot of time to methodical work. That is, when discovering the effect, Michael tried to study it as deeply as possible, to find out all the parameters and characteristics.

Since Michael Faraday made the discovery of electromagnetic induction, and he is considered the founder of the doctrine of the electromagnetic field, his discoveries are important:

• The scientist created the first model of an electric motor.
• Invented the electric motor and transformer.
• He discovered the chemical effect of current and the effect of a magnetic field on light.
• He discovered the laws of diamagnetism and electrolysis.
• predicted electromagnetic waves.
• He discovered rotations of the plane of polarization of light in a magnetic field. This phenomenon was later named after him - the Faraday effect.
• Discovered isobutylene and benzene.
• He introduced such terms into science as cathode, anode, ion, electrolyte, paramagnetism, dielectric and diamagnetism.

Faraday in 1836 proved the following - an electric charge acts exclusively on the surface of a closed-type conductor shell, without exerting absolutely any effect on the objects inside the shell. He made this discovery thanks to experiments carried out in a device invented by himself - in the "Faraday cage".

Often the government involved a physicist in solving various technical problems, for example, how to protect ships from corrosion, the examination of court cases, the improvement of lighthouses, and the like.

September 22, 2011 marked the 220th anniversary of the birth of Michael Faraday (1791–1867), an English experimental physicist who introduced the concept of "field" into science and laid the foundations for the concept of the physical reality of electric and magnetic fields. Nowadays, the concept of a field is known to any high school student. Initial information about electric and magnetic fields and methods for describing them using lines of force, strengths, potentials, etc. have long been included in school textbooks in physics. In the same textbooks, one can read that the field is a special form of matter, fundamentally different from matter. But with the explanation of what exactly this “speciality” consists of, serious difficulties arise. Naturally, the authors of textbooks cannot be blamed for this. After all, if the field is not reducible to some other, simpler entities, then there is nothing to explain. You just need to accept the physical reality of the field as an experimentally established fact and learn how to work with the equations that describe the behavior of this object. For example, Richard Feynman calls for this in his Lectures, noting that scientists have long tried to explain the electromagnetic field using various mechanical models, but then abandoned this idea and considered that only the system of famous Maxwell equations describing the field has physical meaning.

Does this mean that we should completely give up trying to understand what a field is? It seems that acquaintance with Michael Faraday's "Experimental Research on Electricity" - a grandiose three-volume work that the brilliant experimenter has been creating for more than 20 years, can provide significant assistance in answering this question. It is here that Faraday introduces the concept of a field and develops step by step the idea of ​​the physical reality of this object. At the same time, it is important to note that Faraday's Experimental Investigations - one of the greatest books in the history of physics - is written in excellent language, does not contain a single formula and is quite accessible to schoolchildren.

Field introduction. Faraday, Thomson and Maxwell

The term "field" (more precisely: "magnetic field", "field of magnetic forces") was introduced by Faraday in 1845 in the course of research into the phenomenon of diamagnetism (the terms "diamagnetism" and "paramagnetism" were also introduced by Faraday) - the effect of weak repulsion by a magnet discovered by the scientist a number of substances. Initially, the field was considered by Faraday as a purely auxiliary concept, in fact a coordinate grid formed by magnetic lines of force and used to describe the nature of the movement of bodies near magnets. Thus, pieces of diamagnetic substances, such as bismuth, moved from the areas of thickening of the lines of force to the areas of their rarefaction and were located perpendicular to the direction of the lines.

Somewhat later, in 1851-1852, when mathematically describing the results of some of Faraday's experiments, the term "field" was occasionally used by the English physicist William Thomson (1824-1907). As for the creator of the theory of the electromagnetic field, James Clerk Maxwell (1831–1879), in his works the term “field” also practically does not occur at first and is used only to refer to that part of space in which magnetic forces can be detected. Only in the work “Dynamical Theory of the Electromagnetic Field” published in 1864–1865, in which the system of “Maxwell’s equations” first appears and the possibility of the existence of electromagnetic waves propagating at the speed of light, the field is spoken of as a physical reality.

This, in brief, is the history of the introduction of the concept of "field" into physics. It can be seen from it that initially this concept was considered as a purely auxiliary one, denoting simply that part of space (it can be unlimited) in which magnetic forces can be detected and their distribution can be depicted using lines of force. (The term "electric field" came into use only after Maxwell's theory of the electromagnetic field.)

It is important to emphasize that neither the lines of force known to physicists before Faraday, nor the field “consisting” of them were considered (and could not be considered!) by the scientific community of the 19th century as a physical reality. Faraday's attempts to talk about the materiality of lines of force (or Maxwell - about the materiality of the field) were perceived by scientists as completely unscientific. Even Thomson, Maxwell's old friend, who himself did a lot to develop the mathematical foundations of field physics (it was Thomson, not Maxwell, who first showed the possibility of "translating" the language of Faraday's lines of force into the language of partial differential equations), called the theory of the electromagnetic field "mathematical nihilism". and refused to acknowledge it for a long time. It is clear that Thomson could act in this way only if he had very serious reasons for doing so. And he had such reasons.

Force field and Newton force

The reason why Thomson could not recognize the reality of lines of force and fields is simple. The lines of force of the electric and magnetic fields are defined as continuous lines drawn in space so that the tangents to them at each point indicate the directions of the electric and magnetic forces acting at that point. The magnitudes and directions of these forces are calculated using the laws of Coulomb, Ampere and Biot-Savart-Laplace. However, these laws are based on the principle of long-range action, which allows the possibility of instantaneous transmission of the action of one body to another over any distance and, thereby, excluding the existence of any material mediators between interacting charges, magnets and currents.

It should be noted that many scientists were skeptical about the principle that bodies in some mysterious way can act where they do not exist. Even Newton, who was the first to use this principle when deriving the law of universal gravitation, believed that some kind of substance could exist between interacting bodies. But the scientist did not want to build hypotheses about it, preferring to develop mathematical theories of laws based on firmly established facts. Newton's followers did the same. According to Maxwell, they literally "swept out of physics" all sorts of invisible atmospheres and outflows, which in the 18th century surrounded magnets and charges by supporters of the concept of short-range action. Nevertheless, in the physics of the 19th century, interest in seemingly forever forgotten ideas is gradually beginning to revive.

One of the most important prerequisites for this revival was the problems that arose when trying to explain new phenomena - primarily the phenomena of electromagnetism - on the basis of the principle of long-range action. These explanations became more and more artificial. So, in 1845, the German physicist Wilhelm Weber (1804–1890) generalized Coulomb's law by introducing into it terms that determine the dependence of the interaction force of electric charges on their relative velocities and accelerations. The physical meaning of such a dependence was incomprehensible, and Weber's additions to Coulomb's law were clearly in the nature of a hypothesis introduced to explain the phenomena of electromagnetic induction.

In the middle of the 19th century, physicists were increasingly aware that when studying the phenomena of electricity and magnetism, experiment and theory began to speak different languages. In principle, scientists were ready to accept the idea of ​​the existence of a substance that transmits the interaction between charges and currents at a finite speed, but they could not accept the idea of ​​the physical reality of the field. First of all, because of the internal inconsistency of this idea. The fact is that in Newton's physics, force is introduced as the cause of the acceleration of a material point. Its (force) value is equal, as is known, to the product of the mass of this point and the acceleration. Thus, force as a physical quantity is determined at the point and at the moment of its action. “Newton himself reminds us,” wrote Maxwell, “that force exists only as long as it acts; its action may be preserved, but the force itself as such is essentially a transient phenomenon.

Trying to consider the field not as a convenient illustration of the nature of the distribution of forces in space, but as a physical object, scientists came into conflict with the original understanding of the force on the basis of which this object was built. At each point, the field is determined by the magnitude and direction of the force acting on the test body (charge, magnetic pole, coil with current). In fact, the field "consists" only of forces, but the force at each point is calculated on the basis of laws according to which it is meaningless to talk about the field as a physical state or process. The field, considered as a reality, would mean the reality of forces that exist outside of any action, which completely contradicted the original definition of force. Maxwell wrote that in cases where we are talking about "conservation of force" and so on, it would be better to use the term "energy". This is certainly correct, but what energy is the energy of the field? By the time Maxwell wrote the above lines, he already knew that the energy density of, for example, an electric field is proportional to the square of the intensity of this field, i.e., again, the force distributed in space.

The concept of instantaneous action at a distance is inextricably linked with the Newtonian understanding of force. After all, if one body acts on another, remote, not instantaneously (in fact, destroying the distance between them), then we will have to consider the force moving in space and decide what “part” of the force causes the observed acceleration and what meaning then the concept has "strength". Or we must admit that the movement of the force (or field) occurs in some special way that does not fit into the framework of Newtonian mechanics.

In 1920, in the article "Aether and the Theory of Relativity", Albert Einstein (1879-1955) wrote that, speaking of the electromagnetic field as a reality, we must admit the existence of a special physical object, which in principle cannot be represented as consisting of particles, the behavior of each of which lends itself to study over time. Einstein later described the creation of the theory of the electromagnetic field as the greatest revolution in our views on the structure of physical reality since the time of Newton. Thanks to this revolution, in physics, along with ideas about the interaction of material points, ideas about fields entered, as if they were not reducible to anything else.

But how was this change in view of reality possible? How did physics manage to go beyond its borders and “see” what for it before as a reality simply did not exist?

An exceptionally important role in the preparation of this revolution was played by Faraday's many years of experiments with lines of force. Thanks to Faraday, these lines, well known to physicists, turned from a way of depicting the distribution of electric and magnetic forces in space into a kind of "bridge", moving along which they managed to penetrate into the world, which is, as it were, "behind the force", into the world in which forces became manifestations of properties fields. It is clear that such a transformation required a very special kind of talent, a talent that Michael Faraday possessed.

Great Experimenter

Michael Faraday was born on September 22, 1791 in a London blacksmith family, which, due to lack of funds, was unable to educate their children. Michael - the third child in the family - did not finish elementary school and at the age of 12 he was apprenticed to a bookbinding workshop. There he got the opportunity to read many books, including popular science, filling in the gaps in his education. Faraday soon began attending the public lectures that were held regularly in London to spread knowledge to the general public.

In 1812, one of the members of the Royal Society of London, who regularly used the services of a bookbinding workshop, invited Faraday to listen to lectures by the famous physicist and chemist Humphry Davy (1778–1829). This moment became a turning point in Faraday's life. The young man was finally carried away by science, and since his term of study in the workshop was ending, Faraday ventured to write to Davy about his desire to do research, attaching carefully bound notes of the scientist's lectures to the letter. Davy, who himself was the son of a poor woodcarver, not only replied to Faraday's letter, but also offered him an assistant position at the Royal Institution in London. Thus began the scientific activity of Faraday, which lasted almost until his death, which occurred on August 25, 1867.

The history of physics knows many outstanding experimenters, but, perhaps, only Faraday was called the Experimenter with a capital letter. And the point is not only in his colossal achievements, among which are the discoveries of the laws of electrolysis and the phenomena of electromagnetic induction, the study of the properties of dielectrics and magnets, and much more. Often important discoveries were made more or less by accident. It is impossible to say the same about Faraday. His research has always been remarkable for its amazing regularity and purposefulness. So, in 1821, Faraday wrote in his working diary that he was beginning to search for a connection between magnetism and electricity and optics. He discovered the first connection 10 years later (the discovery of electromagnetic induction), and the second - 23 years later (the discovery of the rotation of the plane of polarization of light in a magnetic field).

Faraday's Experimental Investigations in Electricity has about 3,500 paragraphs, many of which contain descriptions of his experiments. And that's just what Faraday saw fit to publish. In the multi-volume "Diaries" of Faraday, which he kept from 1821, about 10 thousand experiments are described, and the scientist performed many of them without anyone's help. Interestingly, in 1991, when the scientific world celebrated the 200th anniversary of Faraday's birth, English historians of physics decided to repeat some of his most famous experiments. But even for a simple reproduction of each of these experiments, a team of modern specialists took at least a day of work.

Speaking about the merits of Faraday, we can say that his main achievement was the transformation of experimental physics into an independent field of research, the results of which can often be many years ahead of the development of theory. Faraday considered the desire of many scientists to move as quickly as possible from the data obtained in experiments to their theoretical generalization as extremely unproductive. More fruitful for Faraday was to maintain a long-term connection with the phenomena under study in order to be able to analyze in detail all their features, regardless of whether these features correspond to accepted theories or not.

Faraday extended this approach to the analysis of experimental data to the well-known experiments on the alignment of iron filings along the magnetic field lines. Of course, the scientist knew perfectly well that the patterns that form iron filings can be easily explained on the basis of the principle of long-range action. Nevertheless, Faraday believed that in this case, experimenters should proceed not from concepts invented by theorists, but from phenomena that, in his opinion, testify to the existence in the space surrounding magnets and currents of some states that are ready for action. In other words, the lines of force, according to Faraday, indicated that force should be thought of not only as an action (on a material point), but also as the ability to act.

It is important to emphasize that, following his methodology, Faraday did not try to put forward any hypotheses about the nature of this ability to act, preferring to gradually accumulate experience in the course of working with lines of force. The beginning of this work was laid in his studies of the phenomena of electromagnetic induction.

Protracted opening

In many textbooks and reference books you can read that on August 29, 1831, Faraday discovered the phenomenon of electromagnetic induction. Historians of science are well aware that the dating of discoveries is complex and often very confusing. The discovery of electromagnetic induction is no exception. It is known from Faraday's Diaries that he observed this phenomenon as early as 1822 during experiments with two conducting circuits put on a soft iron core. The first circuit was connected to a current source, and the second - to a galvanometer, which recorded the occurrence of short-term currents when the current was turned on or off in the first circuit. Later it turned out that similar phenomena were observed by other scientists, but, like Faraday at first, they considered them an experimental error.

The fact is that in search of the phenomena of generation of electricity by magnetism, scientists were aimed at discovering stable effects, similar, for example, to the phenomenon of the magnetic action of current discovered by Oersted in 1818. Faraday was saved from this universal "blindness" by two circumstances. First, close attention to any natural phenomena. In his articles, Faraday reported on both successful and unsuccessful experiments, believing that an unsuccessful (not revealing the desired effect), but meaningfully staged experiment also contains some information about the laws of nature. Secondly, shortly before the discovery, Faraday experimented a lot with the discharges of capacitors, which undoubtedly sharpened his attention to short-term effects. Regularly looking through his diaries (for Faraday this was a constant part of research), the scientist, apparently, took a fresh look at the experiments of 1822 and, having reproduced them, realized that he was dealing not with interference, but with the desired phenomenon. The date of this realization was August 29, 1831.

Then intensive research began, during which Faraday discovered and described the main phenomena of electromagnetic induction, including the occurrence of induction currents during the relative motion of conductors and magnets. Based on these studies, Faraday came to the conclusion that the decisive condition for the occurrence of induction currents is precisely intersection a conductor of lines of magnetic force, and not a transition to areas of greater or lesser forces. At the same time, for example, the occurrence of a current in one conductor when the current is turned on in another, located nearby, Faraday also explained as a result of the conductor crossing the lines of force: “magnetic curves seem to move (so to speak) across the induced wire, starting from the moment when they begin to develop, and up to the moment when the magnetic strength of the current reaches its greatest value; they seem to propagate to the sides of the wire and, therefore, are in relation to the fixed wire in the same position, as if it were moving in the opposite direction across them.

Let us pay attention to how many times Faraday uses the words “as if” in the above passage, and also to the fact that he does not yet have the quantitative formulation of the law of electromagnetic induction familiar to us: the current strength in a conducting circuit is proportional to the rate of change in the number of magnetic field lines passing through through this loop. A formulation close to this appears in Faraday only in 1851, and it refers only to the case of the conductor moving in a static magnetic field. According to Faraday, if a conductor moves in such a field at a constant speed, then the strength of the electric current arising in it is proportional to this speed, and the amount of electricity set in motion is proportional to the number of magnetic field lines crossed by the conductor.

Faraday's caution in formulating the law of electromagnetic induction is primarily due to the fact that he could correctly use the concept of a line of force only in relation to static fields. In the case of variable fields, however, this concept acquired a metaphorical character, and the continuous reservations “as if”, when talking about moving lines of force, show that Faraday understood this very well. He also could not ignore the criticism of those scientists who pointed out to him that the line of force is, strictly speaking, a geometric object, and it is simply meaningless to talk about its movement. In addition, in experiments we are dealing with charged bodies, conductors with current, etc., and not with abstractions like lines of force. Therefore, Faraday had to show that when studying at least some classes of phenomena, one cannot confine oneself to the consideration of current-carrying conductors and not take into account the space surrounding them. So, in a work devoted to the study of the phenomena of self-induction, without ever mentioning lines of force, Faraday builds a story about his experiments in such a way that the reader himself gradually comes to the conclusion that the real cause of the observed phenomena is not conductors with current, but something located in the space around them.

The field is like a premonition. Research on the phenomena of self-induction

In 1834, Faraday published the nineth part of "Experimental Investigations", which was called "On the inductive effect of an electric current on itself and on the inductive effect of currents in general." In this work, Faraday investigated the phenomena of self-induction, discovered in 1832 by the American physicist Joseph Henry (1797–1878), and showed that they represent a special case of the electromagnetic induction phenomena he had previously studied.

Faraday begins his work with a description of a number of phenomena, consisting in the fact that when an electrical circuit containing long conductors or an electromagnet winding is opened, a spark occurs at the contact break point or an electric shock is felt if the contact is disconnected by hand. At the same time, Faraday points out, if the conductor is short, then it is not possible to get a spark or an electric shock by any tricks. Thus, it turned out that the occurrence of a spark (or impact) depends not so much on the strength of the current flowing through the conductor before breaking the contact, but on the length and configuration of this conductor. Therefore, Faraday, first of all, seeks to show that, although the initial cause of the spark is the current (if there was no spark at all in the circuit, then, of course, there will be no spark), the strength of the current is not of decisive importance. To do this, Faraday describes a sequence of experiments in which the length of the conductor is first increased, resulting in an amplification of the spark, despite the weakening of the current in the circuit due to the increase in resistance. Then this conductor is twisted so that the current flows through only a small part of it. At the same time, the current strength increases sharply, but the spark disappears when the circuit is opened. Thus, neither the conductor itself nor the strength of the current in it can be considered as the cause of the spark, the magnitude of which, as it turns out, depends not only on the length of the conductor, but also on its configuration. So, when the conductor is coiled into a spiral, as well as when an iron core is introduced into this spiral, the magnitude of the spark also increases.

In continuation of the study of these phenomena, Faraday connected an auxiliary short conductor parallel to the place where the contact was opened, the resistance of which is much greater than that of the main conductor, but less than that of the spark gap or the body of the person opening the contact. As a result, the spark disappeared when the contact was opened, and a strong short-term current arose in the auxiliary conductor (Faraday calls it extra current), the direction of which turned out to be opposite to the direction of the current that would flow through it from the source. “These experiments,” writes Faraday, “establish a significant difference between the primary, or exciting, current and extra current in terms of quantity, intensity, and even direction; they led me to the conclusion that the extra current is identical with the induced current I described earlier.

Having put forward the idea of ​​the connection of the studied phenomena with the phenomena of electromagnetic induction, Faraday further set up a number of ingenious experiments confirming this idea. In one of these experiments, another open coil was placed next to a coil connected to a current source. When disconnected from the current source, the first coil gave a strong spark. However, if the ends of the other spiral closed, the spark practically disappeared, and a short-term current arose in the second spiral, the direction of which coincided with the direction of the current in the first spiral if the circuit was opened, and was opposite to it if the circuit was closed.

Having established the connection between the two classes of phenomena, Faraday was able to easily explain the experiments performed earlier, namely, the amplification of a spark when a conductor is lengthened, coiled into a spiral, an iron core is introduced into it, etc.: “If we observe the inductive action of a wire one foot long on a near the wire is also one foot long, then it turns out to be very weak; but if the same current is passed through a wire fifty feet long, it will induce in the adjacent fifty-foot wire, at the moment of making or breaking the contact, a much stronger current, as if every extra foot of wire added something to the total effect; by analogy, we conclude that the same phenomenon must also take place when the connecting conductor serves at the same time as a conductor in which an induced current is formed. Therefore, Faraday concludes, increasing the length of the conductor, folding it into a spiral and introducing a core into it strengthens the spark. To the action of one turn of the spiral on another, the action of the demagnetizing core is added. At the same time, the totality of such actions can compensate each other. For example, if a long insulated wire is folded in half, then due to the opposite inductive action of its two halves, the spark will disappear, although in the straightened state this wire gives a strong spark. The replacement of the iron core with a steel core, which demagnetizes very slowly, also led to a significant weakening of the spark.

So, leading the reader through detailed descriptions of the sets of experiments performed, Faraday, without saying a word about the field, formed in him, the reader, the idea that the decisive role in the phenomena under study belongs not to conductors with current, but to some kind created by them in the surrounding space. then the state of magnetization, more precisely, the rate of change of this state. However, the question of whether this state really exists and whether it can be the subject of experimental studies remained open.

The problem of the physical reality of lines of force

Faraday managed to take a significant step in proving the reality of lines of force in 1851, when he came up with the idea of ​​generalizing the concept of a line of force. “A magnetic line of force,” Faraday wrote, “can be defined as the line that a small magnetic needle describes when it is moved in one direction or another in the direction of its length, so that the arrow remains tangent to the movement all the time; or, in other words, this is the line along which a transverse wire can be moved in any direction, and in the latter there will be no desire to generate any current, while when it is moved in any other direction, such a desire exists.

The line of force was thus defined by Faraday on the basis of two different laws (and understandings) of the action of a magnetic force: its mechanical action on a magnetic needle and its ability (in accordance with the law of electromagnetic induction) to generate an electric force. This double definition of the line of force, as it were, "materialized" it, gave it the meaning of special, experimentally detected directions in space. Therefore, Faraday called such lines of force "physical", believing that he would now be able to finally prove their reality. The conductor in such a double definition could be represented as closed and sliding along the lines of force so that, being constantly deformed, it would not cross the lines. This conductor would single out a certain conditional "number" of lines that are preserved when they are "thickened" or "rarefied". Such sliding of a conductor in the field of magnetic forces without the appearance of an electric current in it could be considered as an experimental proof of the conservation of the number of lines of force during their "spread", for example, from the pole of a magnet, and, thus, as proof of the reality of these lines.

Of course, a real conductor is practically impossible to move so that it does not cross the lines of force. Therefore, Faraday substantiated the hypothesis about the conservation of their number differently. Let a magnet with pole N and a conductor abcd located so that they can rotate relative to each other around the axis ad(Fig. 1; the drawing was made by the author of the article based on Faraday's drawings). In this case, part of the conductor ad passes through the hole in the magnet and has free contact at the point d. Free contact is made and at the point c, so the plot bc can rotate around the magnet without breaking the electrical circuit connected at the points a and b(also by means of sliding contacts) to the galvanometer. Conductor bc with full rotation around the axis ad intersects all lines of force emanating from the pole of the magnet N. Now let the conductor rotate at a constant speed. Then, comparing the readings of the galvanometer at different positions of the rotating conductor, for example, in the position abcd and pregnant ab"c"d, when the conductor for a full turn again crosses all the lines of force, but already in places of their greater rarefaction, it can be found that the readings of the galvanometer are the same. According to Faraday, this indicates the preservation of a certain conditional number of lines of force, which can characterize the north pole of the magnet (the larger this "number", the stronger the magnet).

Rotating in his installation (Fig. 2; Faraday's drawing) not a conductor, but a magnet, Faraday comes to the conclusion that the number of lines of force in the inner region of the magnet is conserved. At the same time, his reasoning is based on the assumption that the lines of force are not entrained by a rotating magnet. These lines remain "in place" while the magnet rotates among them. In this case, the current in magnitude is the same as when the external conductor rotates. Faraday explains this result by saying that although the outer part of the conductor does not cross the lines, its inner part ( cd), rotating with the magnet, intersects all lines passing inside the magnet. If the outer part of the conductor is fixed and rotated together with the magnet, then no current occurs. This can also be explained. Indeed, the inner and outer parts of the conductor cross the same number of lines of force directed in the same direction, so the currents induced in both parts of the conductor cancel each other out.

It followed from the experiments that inside the magnet the lines of force do not go from the north pole to the south, but vice versa, forming closed curves with external lines of force, which allowed Faraday to formulate the law of conservation of the number of magnetic lines of force in the external and internal spaces of a permanent magnet: “This amazing distribution force, which is revealed by means of a moving conductor, a magnet is exactly like an electromagnetic coil, both in the fact that the lines of force flow in the form of closed circles, and in the equality of their sum inside and outside. Thus, the concept of "number of lines of force" received the rights of citizenship, due to which the formulation of the law of proportionality of the electromotive force of induction to the number of lines of force crossed by the conductor per unit time acquired physical meaning.

However, Faraday admitted that his results are not the final proof of the reality of lines of force. For such a proof, he wrote, it is necessary "to establish the ratio of lines of force to time", i.e., to show that these lines can move in space with a finite speed and, therefore, can be detected by any physical methods.

It is important to emphasize that the problem of "physical lines of force" had nothing to do with Faraday's attempts to directly detect ordinary lines of force. Since the discovery of electromagnetic induction, Faraday believed that both ordinary lines of force and the laws of electromagnetism are manifestations of some special properties of matter, its special state, which the scientist called electrotonic. At the same time, the question of the essence of this state and its connection with known forms of matter was, Faraday considered, open: “What is this state and what does it depend on, we cannot say now. Maybe it is due to the ether, like a light beam... Maybe it is a state of tension, or a state of vibration, or some other state analogous to the electric current, with which the magnetic forces are so closely associated. Whether the presence of matter is necessary to maintain this state depends on what is meant by the word "matter". If the concept of matter is limited to weighty or gravitating substances, then the presence of matter is just as little essential for physical lines of magnetic force as it is for rays of light and heat. But if, admitting the ether, we accept that this is a kind of matter, then the lines of force may depend on any of its actions.

Such close attention that Faraday paid to the lines of force was due primarily to the fact that he saw them as a bridge leading to some completely new world. However, it was difficult even for such a brilliant experimenter as Faraday to cross this bridge. Actually, this problem did not allow a purely experimental solution at all. However, one could try to penetrate mathematically into the space between the lines of force. This is exactly what Maxwell did. His famous equations became the tool that made it possible to penetrate into the non-existent gaps between Faraday's lines of force and, as a result, discover a new physical reality there. But this is another story - the story of the Great Theorist.

This refers to the book by R. Feynman, R. Leighton and M. Sands "Feynman Lectures on Physics" (M.: Mir, 1967) ( Note. ed.)
In Russian translation, the first volume of this book was published in 1947, the second - in 1951, and the third - in 1959 in the series "Classics of Science" (M.: Izdatelstvo AN SSSR). ( Note. ed.)
In 1892, William Thomson was awarded the noble title "Lord Kelvin" for fundamental work in various fields of physics, in particular, the laying of a transatlantic cable linking England and the United States.

Michael Faraday is an English scientist who became famous for his research in the field of magnetism and electric current. Each of his discoveries took science one step further and eventually led to electricity, the computer, and many of the essentials of modern life.

The life of Michael Faraday began in one of the poorest areas of London on September 22, 1791. His father and brother worked as blacksmiths, but their earnings were barely enough to support the family. As a result of the plight, the boy did not even receive a secondary education, limiting himself only to the local primary school. From the moment of her graduation, Michael was engaged in his studies on his own, loved to read books, was fond of the natural sciences, in particular, chemistry and physics.

To alleviate the situation of the family, from the age of 13, young Faraday himself begins to earn money. At first he worked as a peddler of books and newspapers, and a year later in the bookstore itself. Here he learns to bind books, while the owner of the shop allows Michael to read them. The boy with great enthusiasm takes up the study of all available materials, tries to apply theoretical knowledge in practice. So he had a whole makeshift laboratory at his house, in which Faraday conducted various scientific experiments.

His older brother also made his contribution to Michael's education - he paid the boy more than once to attend lectures in physics, chemistry and astronomy. However, Faraday got to the main lecture in his life absolutely by accident. One of the buyers in the bookstore noticed Michael's interest in science and gave him invitation cards to a lecture by Humphrey Davy. After her visit, the young man personally bound his abstract and, gathering his courage, sent it to the teacher. He, in turn, approved of the boy's knowledge of physics and, after a little thought, invited Faraday to work as his assistant at Queen's University.

Starting in 1813, Davy, along with his assistant, traveled extensively in Europe. So Faraday managed to visit the best laboratories in France and Italy, as well as get acquainted with the great scientists of that time: M. Chevrel, J. L. Gay-Lussac, A. Ampère. The whole trip took more than two years and further ignited the craving for science in the young scientist.

In 1815, returning to the university, Michael Faraday threw himself into work. He devotes more and more time to his own research, however, he manages to give free lectures for those who, like himself, are forced to educate themselves. Thus, the scientist contributes to the popularization of science and develops his oratorical talent.

In 1820, Oersted's works fell into the hands of Faraday, which dealt with the magnetic effect of electric current. From that moment on, the scientist is seriously studying this issue, and, after 10 years of painstaking work, he comes to the concept of electromagnetic induction (the interaction of magnetism and electric current). Henry's coil helped him make a great discovery.

A year later, Michael Faraday becomes a technical supervisor at Queen's University. His responsibilities include overseeing all of his laboratories. The year 1821 was also significant in Faraday's personal life - he got married and, according to his contemporaries, it was a very successful and happy marriage.

In the same year he published two of his famous works: on the liquefaction of chlorine and on electromagnetic motions. The first led him to convert chlorine into a liquid substance (1824), and the second dealt with the prototype of an electric motor. It described an experiment with a magnetized needle, which Faraday forced to rotate around a magnetic pole. For this experience, Michael was groundlessly accused of plagiarism by W. Wollaston. At the same time, Faraday's mentor - G. Davy - did not support his student, and took the side of the famous scientist.

He did not take the side of Faraday in 1824 either. When the scientist was accepted into the Royal Society of London, Davy was the only one who voted against his membership. However, this did not stop Davy from calling Faraday his most important discovery.

In 1825, Faraday became director of the laboratory at the Royal University, and in 1827 he became a professor and head of the department of chemistry.

In 1832, continuing research related to electric current, Faraday came to the concept of electrolysis. This phenomenon makes it possible to pass current through various solutions, separating valuable components from them. It is used to this day in the chemical industry and metallurgy. In the same period, Faraday made another important discovery - he was able to prove the identity of all manifestations of electricity.

In 1835, Faraday's friends obtained a lifetime pension from the Minister of the Treasury for the scientist for his scientific discoveries. Despite the plight, Faraday did not accept the "handout", agreeing to payments only after the minister's apology and sincere recognition of his merits.

In 1840, Faraday voiced the theory of the unity of all existing energies. He claimed that all of them can turn into one another. Thus, he came to the concept of lines of force. At that moment, the scientist suffered a misfortune - he became seriously ill and left his scientific activity for five years. Therefore, the term "magnetic field" appeared only in 1845. At the same time, Faraday discovered dia- and paramagnetism.

In 1848, the so-called Faraday effect was discovered, which connected magnetism and optics. In fact, it was the polarization of light, its interaction with the magnetic field lines. The scientist himself described his discovery in the following words: "I magnetized the light."

The disease, which had receded for a while, returned again in 1855. Faraday is increasingly suffering from headaches, begins to lose his memory. At the same time, he continues to engage in science to the last, carefully outlining his thoughts in a laboratory journal.

Michael Faraday died on August 25, 1867 at Hampton Court, but his discoveries are still alive today. Without him, such integral things of modern life as electricity, a computer, aluminum spoons, copper wires, stainless steel, an electric motor, etc. would not exist. One of the most prestigious awards for achievements in science, the Faraday medal, is named after him.

“As long as people enjoy the benefits of electricity, they will always remember Faraday's name with gratitude,” said Hermann Helmholtz.

Michael Faraday - English experimental physicist, chemist, creator of the theory of the electromagnetic field. He discovered electromagnetic induction, which is the basis of the industrial production of electricity and applications in modern conditions.

Childhood and youth

Michael Faraday was born on September 22, 1791 in Newington Butts, near London. Father - James Faraday (1761-1810), blacksmith. Mom - Margaret (1764-1838). In addition to Michael, brother Robert and sisters Elizabeth and Margaret grew up in the family. They lived in poverty, so Michael did not finish his studies at school and at the age of 13 he went to work in a bookstore as a messenger.

Education was not completed. The craving for knowledge was satisfied by reading books on physics and chemistry - there were plenty of such books in the bookstore. The young man mastered the first experiments. He built a current source - "Leiden jar". Father and brother supported Michael in his craving for experiments.

In 1810, the 19-year-old youth became a member of the Philosophical Club, where lectures were given on physics and astronomy. Michael participated in scientific controversy. The gifted young man attracted the attention of the scientific community. Bookstore buyer William Dens gave Michael a gift - a ticket to attend a series of lectures on chemistry and physics by Humphry Davy (the founder of electrochemistry, the discoverer of the chemical elements Potassium, Calcium, Sodium, Barium, Boron).

The future scientist, having shorthanded Humphry Davy's lectures, made a binding and sent it to the professor, accompanied by a letter asking him to find some work at the Royal Institute. Davy took part in the fate of the young man, and after a while the 22-year-old Faraday got a job as a laboratory assistant in a chemical laboratory.

The science

Performing the duties of a laboratory assistant, Faraday did not miss the opportunity to listen to lectures, in the preparation of which he participated. Also, with the blessing of Professor Davy, the young man conducted his chemical experiments. The conscientiousness and skillfulness of performing the work as a laboratory assistant made him Davy's constant assistant.

In 1813, Davy took Faraday as his secretary on a two-year European trip. During the trip, the young scientist met the luminaries of world science: Andre-Marie Ampère, Joseph Louis Gay-Lussac, Alessandro Volta.

Upon his return to London in 1815, Faraday received a position as an assistant. In parallel, he continued his favorite business - he set up his own experiments. During his life, Faraday conducted 30,000 experiments. In scientific circles, for his pedantry and diligence, he received the title of "king of experimenters." The description of each experience was carefully recorded in the diaries. Later, in 1931, these diaries were published.

The first printed edition of Faraday appeared in 1816. By 1819, 40 works had been printed. The works are devoted to chemistry. In 1820, from a series of experiments with alloys, a young scientist discovered that an alloy of steel with the addition of nickel did not give oxidation. But the results of the experiments passed by metallurgists. The discovery of stainless steel was patented much later.

In 1820 Faraday became the technical superintendent of the Royal Institute. By 1821 he had moved from chemistry to physics. Faraday acted as an established scientist, gained weight in the scientific community. An article was published on the principle of operation of an electric motor, which marked the beginning of industrial electrical engineering.

Electromagnetic field

In 1820, Faraday became interested in experiments on the interaction of electricity and a magnetic field. By this time, the concepts of "direct current source" (A. Volt), "electrolysis", "electric arc", "electromagnet" had been discovered. During this period, electrostatics and electrodynamics developed, the experiments of Biot, Savart, Laplace on working with electricity and magnetism were published. A. Ampere's work on electromagnetism has been published.

In 1821, Faraday's work "On Some New Electromagnetic Motions and on the Theory of Magnetism" saw the light of day. In it, the scientist presented experiments with a magnetic needle rotating around one pole, i.e., he converted electrical energy into mechanical energy. In fact, he introduced the world's first, albeit primitive, electric motor.

The joy of discovery was spoiled by the complaint of William Wollaston (discovered Palladium, Rhodium, designed a refractometer and a goniometer). In a complaint to Professor Davy, the scientist accused Faraday of stealing the spinning magnetic needle idea. The story took on a scandalous character. Davy accepted Wollaston's position. Only a personal meeting of two scientists and Faraday's explanation of his position was able to resolve the conflict. Wollaston retracted his claims. The relationship between Davy and Faraday has lost its former trust. Although the first did not tire of repeating until the last days that Faraday was the main discovery he made.

In January 1824, Faraday was elected a member of the Royal Society of London. Professor Davy voted against.

In 1823 he became a corresponding member of the Paris Academy of Sciences.

In 1825, Michael Faraday took Davy's place as director of the laboratory of physics and chemistry at the Royal Institution.

After the discovery of 1821, the scientist did not publish works for ten years. In 1831 he became a professor at Woolwich (military academy), in 1833 a professor of chemistry at the Royal Institution. Conducted scientific debates, lectured at scientific meetings.

Back in 1820, Faraday was interested in the experience of Hans Oersted: movement along an electric current circuit caused the movement of a magnetic needle. Electric current was the cause of magnetism. Faraday suggested that, accordingly, magnetism could be the cause of the electric current. The first mention of the theory appeared in the diary of a scientist in 1822. It took ten years of experiments to unravel the mystery of electromagnetic induction.

The victory came on August 29, 1831. The device that allowed Faraday to make a brilliant discovery consisted of an iron ring and many turns of copper wire wound around its two halves. In the circuit of one half of the ring, closed by a wire, there was a magnetic needle. The second winding was connected to the battery. When the current is turned on, the magnetic needle oscillates in one direction, and when it is turned off, it oscillates in the other direction. Faraday concluded that a magnet is capable of converting magnetism into electrical energy.

The phenomenon of "the appearance of an electric current in a closed circuit with a change in the magnetic flux passing through it" was called electromagnetic induction. The discovery of electromagnetic induction opened the way for the creation of a current source - an electric generator.

The discovery marked the beginning of a new fruitful round of the scientist's experiments, which gave the world "Experimental Research on Electricity". Faraday empirically proved the unified nature of the occurrence of electrical energy, independent of the method by which the electric current is caused.

In 1832, the physicist was awarded the Copley medal.

Faraday became the author of the first transformer. He owns the concept of "dielectric permittivity". In 1836, through a series of experiments, he proved that the charge of the current affects only the shell of the conductor, leaving the objects inside it intact. In applied science, a device based on the principle of this phenomenon is called a "Faraday cage".

Discoveries and works

The discoveries of Michael Faraday are not only about physics. In 1824 he discovered benzene and isobutylene. The scientist deduced the liquid form of chlorine, hydrogen sulfide, carbon dioxide, ammonia, ethylene, nitrogen dioxide, obtained the synthesis of hexachlorane.

In 1835, due to illness, Faraday was forced to take a two-year break from work. The cause of the disease was suspected to be contact of a scientist during experiments with mercury vapor. After working for a short time after his recovery, in 1840 the professor again felt unwell. I was haunted by weakness, there was a temporary loss of memory. The recovery period was delayed for 4 years. In 1841, at the insistence of doctors, the scientist went on a trip to Europe.

The family lived almost in poverty. According to Faraday's biographer John Tyndall, the scientist received a pension of 22 pounds a year. In 1841, Prime Minister William Lamb, Lord Melbourne, under public pressure, signed a decree granting Faraday a state pension of £300 a year.

In 1845, the great scientist managed to attract the attention of the world community with some more discoveries: the discovery of a change in the plane of polarized light in a magnetic field (“Faraday effect”) and diamagnetism (magnetization of a substance to an external magnetic field acting on it).

The British government has repeatedly asked Michael Faraday for help in solving problems related to technical issues. The scientist developed a program for equipping lighthouses, methods for combating ship corrosion, and acted as a forensic expert. Being by nature a good-natured and peaceful person, he flatly refused to participate in the creation of chemical weapons for the war with Russia in the Crimean War.

In 1848, she gave Faraday a house on the left bank of the Thames, Hampton Court. The British queen paid expenses and taxes around the house. The scientist and his family moved into it, leaving business in 1858.

Personal life

Michael Faraday was married to Sarah Barnard (1800-1879). Sarah is the sister of Faraday's friend. The 20-year-old girl did not immediately accept the marriage proposal - the young scientist had to worry. The silent wedding took place on June 12, 1821. Many years later Faraday wrote:

"I got married - an event that, more than any other, contributed to my happiness on earth and my healthy state of mind."

The Faraday family, like his wife's family, are members of the Sandemanian Protestant community. Faraday performed the work of the deacon of the London community, was repeatedly elected elder.

Death

Michael Faraday was sick. In the brief moments when the disease receded, he worked. In 1862, he put forward a hypothesis about the movement of spectral lines in a magnetic field. Peter Zeeman was able to confirm the theory in 1897, for which he received the Nobel Prize in 1902. Faraday Zeeman called the author of the idea.

Michael Faraday died at his desk on August 25, 1867 at the age of 75. He was buried next to his wife at Highgate Cemetery in London. The scientist asked before his death for a modest funeral, so only relatives came. The name of the scientist and the years of his life are carved on the tombstone.

• In his work, the physicist did not forget about children. Lectures for children "The History of the Candle" (1961) are being republished to this day.
• Faraday's portrait is featured on the 1991-1999 British £20 note.
• It was rumored that Davy did not respond to Faraday's request for a job. Once, having temporarily lost his sight during a chemical experiment, the professor remembered the persistent young man. After working as a scientist's secretary, the young man shocked Davy with his erudition so much that he offered Michael a job in the laboratory.
• After returning from a European tour with Davy's family, Faraday worked there as a dishwasher while waiting for an assistant position at the Royal Institution.