Faraday. discovery of electromagnetic induction

After the discoveries Oersted And Ampere It became clear that electricity has magnetic force. Now it was necessary to confirm the influence of magnetic phenomena on electrical ones. Faraday brilliantly solved this problem.

Michael Faraday (1791-1867) was born in London, in one of its poorest parts. His father was a blacksmith, and his mother was the daughter of a tenant farmer. When Faraday reached school age, he was sent to elementary school. The course Faraday took here was very narrow and was limited only to learning to read, write and begin to count.

A few steps from the house in which the Faraday family lived, there was a bookshop, which was also a bookbinding establishment. This is where Faraday ended up after completing his course primary school, when the question arose about choosing a profession for him. Michael was only 13 years old at this time. Already in his youth, when Faraday was just beginning his self-education, he sought to rely exclusively on facts and verify the messages of others with his own experiences.

These aspirations dominated him all his life as the main features of his scientific activity. Faraday began to carry out physical and chemical experiments as a boy at his first acquaintance with physics and chemistry. One day Michael attended one of the lectures Humphry Davy, the great English physicist.

Faraday made a detailed note of the lecture, bound it and sent it to Davy. He was so impressed that he invited Faraday to work with him as a secretary. Soon Davy went on a trip to Europe and took Faraday with him. Over the course of two years, they visited the largest European universities.

Returning to London in 1815, Faraday began working as an assistant in one of the laboratories of the Royal Institution in London. At that time it was one of the best physics laboratories in the world. From 1816 to 1818, Faraday published a number of small notes and short memoirs on chemistry. Faraday's first work on physics dates back to 1818.

Based on the experiences of his predecessors and combining several of his own experiences, by September 1821 Michael published "The history of the success of electromagnetism". Already at this time, he formed a completely correct concept of the essence of the phenomenon of deflection of a magnetic needle under the influence of current.

Having achieved this success, Faraday left his studies in the field of electricity for ten years, devoting himself to the study of a number of subjects of a different kind. In 1823, Faraday made one of the most important discoveries in the field of physics - he was the first to liquefy gas, and at the same time established a simple but effective method for converting gases into liquid. In 1824, Faraday made several discoveries in the field of physics.

Among other things, he established the fact that light affects the color of glass, changing it. IN next year Faraday again turned from physics to chemistry, and the result of his work in this area was the discovery of gasoline and sulfur-naphthalene acid.

In 1831, Faraday published a treatise “On a Special Kind of Optical Illusion,” which served as the basis for an excellent and curious optical projectile called the “chromotrope.” In the same year, another treatise by the scientist, “On Vibrating Plates,” was published. Many of these works could themselves immortalize the name of their author. But the most important of scientific works Faraday are his research in the field of electromagnetism and electrical induction.

Strictly speaking, an important branch of physics that treats the phenomena of electromagnetism and inductive electricity, and which is currently of such enormous importance for technology, was created by Faraday out of nothing.

By the time Faraday finally devoted himself to research in the field of electricity, it was established that under ordinary conditions the presence of an electrified body is sufficient for its influence to excite electricity in any other body. At the same time, it was known that a wire through which current passes and which also represents an electrified body does not have any effect on other wires placed nearby.

What caused this exception? This is the question that interested Faraday and the solution of which led him to the most important discoveries in the field of induction electricity. As was his custom, Faraday began a series of experiments designed to clarify the essence of the matter.

Faraday wound two insulated wires parallel to each other on the same wooden rolling pin. He connected the ends of one wire to a battery of ten cells, and the ends of the other to a sensitive galvanometer. When current was passed through the first wire,

Faraday turned all his attention to the galvanometer, expecting to notice from its vibrations the appearance of a current in the second wire. However, nothing of the kind happened: the galvanometer remained calm. Faraday decided to increase the current strength and introduced 120 galvanic elements into the circuit. The result was the same. Faraday repeated this experiment dozens of times and still with the same success.

Anyone else in his place would have left the experiments convinced that the current passing through a wire has no effect on the neighboring wire. But Faraday always tried to extract from his experiments and observations everything that they could give, and therefore, not receiving a direct effect on the wire connected to the galvanometer, he began to look for side effects.

He immediately noticed that the galvanometer, remaining completely calm during the entire passage of current, begins to oscillate when the circuit itself is closed and when it is opened. It turned out that at the moment when a current is passed into the first wire, and also when this transmission stops, at the second wire is also excited by a current, which in the first case has the opposite direction to the first current and the same with it in the second case and lasts only one instant.

These secondary instantaneous currents, caused by the influence of the primary ones, were called inductive by Faraday, and this name has remained with them to this day. Being instantaneous, instantly disappearing after their appearance, inductive currents would have no practical significance if Faraday had not found a way, with the help of an ingenious device (a commutator), to constantly interrupt and re-conduct the primary current coming from the battery along the first wire, thanks to which the second wire is continuously excited by more and more new inductive currents, thus becoming constant. Thus a new source was found electrical energy, in addition to previously known (friction and chemical processes), - induction, and the new kind this energy - induction electricity.

Continuing his experiments, Faraday further discovered that simply bringing a wire twisted into a closed curve close to another through which a galvanic current flows is sufficient to excite an inductive current in the neutral wire in the direction opposite to the galvanic current, and that removing the neutral wire again excites an inductive current in it. the current is already in the same direction as the galvanic current flowing along a stationary wire, and that, finally, these inductive currents are excited only during the approach and removal of the wire to the conductor of the galvanic current, and without this movement the currents are not excited, no matter how close the wires are to each other .

Thus, a new phenomenon was discovered, similar to the above-described phenomenon of induction when the galvanic current closes and stops. These discoveries in turn gave rise to new ones. If it is possible to cause an inductive current by short-circuiting and stopping the galvanic current, then wouldn’t the same result be obtained by magnetizing and demagnetizing iron?

The work of Oersted and Ampere had already established the relationship between magnetism and electricity. It was known that iron becomes a magnet when an insulated wire is wound around it and a galvanic current passes through the latter, and that magnetic properties of this iron stop as soon as the current stops.

Based on this, Faraday came up with this kind of experiment: two insulated wires were wound around an iron ring; with one wire wrapped around one half of the ring, and the other around the other. Current from a galvanic battery was passed through one wire, and the ends of the other were connected to a galvanometer. And so, when the current closed or stopped and when, consequently, the iron ring was magnetized or demagnetized, the galvanometer needle quickly oscillated and then quickly stopped, that is, the same instantaneous inductive currents were excited in the neutral wire - this time: already under the influence of magnetism.

Thus, here for the first time magnetism was converted into electricity. Having received these results, Faraday decided to diversify his experiments. Instead of an iron ring, he began to use an iron strip. Instead of exciting magnetism in iron by galvanic current, he magnetized the iron by touching it to a permanent steel magnet. The result was the same: always in the wire wrapped around the iron! a current was excited at the moment of magnetization and demagnetization of iron.

Then Faraday introduced a steel magnet into the wire spiral - the approach and removal of the latter caused induced currents in the wire. In a word, magnetism, in the sense of exciting induction currents, acted in exactly the same way as galvanic current.

FARADAY. DISCOVERY OF ELECTROMAGNETIC INDUCTION

Obsessed with ideas about the inextricable connection and interaction of the forces of nature, Faraday tried to prove that just as Ampere could create magnets with the help of electricity, so it was possible to create electricity with the help of magnets.

His logic was simple: mechanical work easily turns into heat; on the contrary, heat can be converted into mechanical work(say, in a steam engine). In general, among the forces of nature, the following relationship most often occurs: if A gives birth to B, then B gives birth to A.

If Ampere obtained magnets with the help of electricity, then, apparently, it is possible to “obtain electricity from ordinary magnetism.” Arago and Ampère set themselves the same task in Paris, and Colladon in Geneva.

Faraday carried out many experiments and kept pedantic notes. He devotes a paragraph to each small study in his laboratory notes (published in London in full in 1931 under the title “Faraday’s Diary”). Faraday’s ability to work is evidenced by the fact that the last paragraph of the “Diary” is marked with the number 16041. Faraday’s brilliant skill as an experimenter, obsession, and clear philosophical position could not but be rewarded, but it took eleven long years to wait for the result.

Apart from his intuitive conviction in the universal connection of phenomena, nothing actually supported him in his search for “electricity from magnetism.” Moreover, like his teacher Davy, he relied more on his experiences than on mental constructs. Davy taught him:

A good experiment is of more value than the profundity of a genius like Newton.

And yet, it was Faraday who was destined for great discoveries. A great realist, he spontaneously broke the empiricist shackles that Davy had once imposed on him, and at those moments a great insight dawned on him - he acquired the ability to make the deepest generalizations.

The first glimmer of luck appeared only on August 29, 1831. On this day, Faraday was testing a simple device in the laboratory: an iron ring with a diameter of about six inches, wrapped in two pieces of insulated wire. When Faraday connected a battery to the terminals of one winding, his assistant, artillery sergeant Andersen, saw the needle of the galvanometer connected to the other winding twitch.

It twitched and calmed down, although the direct current continued to flow through the first winding. Faraday carefully examined all the details of this simple installation - everything was in order.

But the galvanometer needle stubbornly stood at zero. Out of frustration, Faraday decided to turn off the current, and then a miracle happened - while opening the circuit, the galvanometer needle swung again and froze at zero again!

Faraday was perplexed: firstly, why is the needle behaving so strangely? Secondly, do the bursts he noticed relate to the phenomenon he was looking for?

It was here that Ampere's great ideas - the connection between electric current and magnetism - were revealed to Faraday in all their clarity. After all, the first winding into which he supplied current immediately became a magnet. If we consider it like a magnet, then the experiment on August 29 showed that magnetism seems to give birth to electricity. Only two things remained strange in this case: why did the surge of electricity when the electromagnet was turned on quickly fade away? And moreover, why does the splash appear when the magnet is turned off?

The next day, August 30, a new series of experiments. The effect is clearly expressed, but nevertheless completely incomprehensible.

Faraday senses that a discovery is somewhere nearby.

“Now I am again studying electromagnetism and I think that I have hit upon a successful thing, but I cannot yet confirm this. It may very well be that after all my labors I will end up with seaweed instead of fish.”

By the next morning, September 24, Faraday had prepared a lot various devices, in which the main elements were no longer windings with electric current, but permanent magnets. And the effect also existed! The arrow deviated and immediately rushed to the spot. This slight movement occurred during the most unexpected manipulations with the magnet, sometimes seemingly by accident.

The next experiment is October 1st. Faraday decides to return to the very beginning - to two windings: one with current, the other connected to the galvanometer. The difference with the first experiment is the absence of a steel ring - core. The splash is almost unnoticeable. The result is trivial. It is clear that a magnet without a core is much weaker than a magnet with a core. Therefore, the effect is less pronounced.

Faraday is disappointed. For two weeks he does not go near the devices, thinking about the reasons for the failure.

Faraday knows in advance how this will happen. The experiment succeeds brilliantly.

“I took a cylindrical magnetic bar (3/4 inch in diameter and 8 1/4 inches long) and inserted one end of it into the spiral of copper wire(220 feet long) connected to a galvanometer. Then I quickly pushed the magnet inside the spiral to its entire length, and the galvanometer needle experienced a push. Then I just as quickly pulled the magnet out of the spiral, and the arrow swung again, but in the opposite side. These swings of the needle were repeated every time the magnet was pushed or pushed out.”

The secret is in the movement of the magnet! The impulse of electricity is determined not by the position of the magnet, but by the movement!

This means that “an electric wave arises only when a magnet moves, and not due to the properties inherent in it at rest.”

This idea is incredibly fruitful. If the movement of a magnet relative to a conductor creates electricity, then apparently the movement of a conductor relative to a magnet should generate electricity! Moreover, this “electric wave” will not disappear as long as the mutual movement of the conductor and magnet continues. This means it is possible to create a generator electric current, acting for as long as desired, as long as the mutual movement of the wire and magnet continues!

On October 28, Faraday installed a rotating copper disk between the poles of a horseshoe magnet, from which electrical voltage could be removed using sliding contacts (one on the axis, the other on the periphery of the disk). It was the first electric generator created by human hands.

After the “electromagnetic epic,” Faraday was forced to stop his scientific work for several years - his nervous system was so exhausted...

Experiments similar to Faraday's, as already mentioned, were carried out in France and Switzerland. Professor Colladon of the Academy of Geneva was a sophisticated experimenter (he, for example, made precise measurements of the speed of sound in water on Lake Geneva). Perhaps, fearing the shaking of the instruments, he, like Faraday, removed the galvanometer from the rest of the installation if possible. Many argued that Colladon observed the same fleeting movements of the needle as Faraday, but, expecting a more stable, long-lasting effect, did not attach due importance to these “random” bursts...

Indeed, the opinion of most scientists of that time was that the reverse effect of “creating electricity from magnetism” should apparently have the same stationary character as the “direct” effect - “formation of magnetism” due to electric current. The unexpected "fleetingness" of this effect confused many, including Colladon, and these many paid for their prejudice.

Faraday was also initially confused by the fleeting nature of the effect, but he trusted facts more than theories, and eventually came to the law electromagnetic induction. This law seemed flawed, ugly, strange, and devoid of internal logic to physicists at that time.

Why is current excited only when the magnet moves or the current changes in the winding?

Nobody understood this. Even Faraday himself. Seventeen years later, a twenty-six-year-old army surgeon at a provincial garrison in Potsdam, Hermann Helmholtz, realized this. In the classic article “On the Conservation of Force,” he, formulating his law of conservation of energy, first proved that electromagnetic induction should exist in precisely this “ugly” form.

Maxwell's older friend, William Thomson, also came to this conclusion independently. He also obtained Faraday's electromagnetic induction from Ampere's law, taking into account the law of conservation of energy.

Thus, “fleeting” electromagnetic induction acquired citizenship rights and was recognized by physicists.

But it did not fit into the concepts and analogies of Maxwell’s article “On Faraday lines of force.” And this was a serious flaw in the article. In practice, its significance was reduced to illustrating the fact that the theories of close- and long-range action represent different mathematical description the same experimental data that Faraday's field lines do not contradict common sense. And it's all. Everything, although it was already a lot.

From Maxwell's book author Kartsev Vladimir Petrovich

TO THE ELECTROMAGNETIC THEORY OF LIGHT The article “On physical lines of force” was published in parts. And the third part of it, like both previous ones, contained new ideas of extreme value. Maxwell wrote: “It must be assumed that the substance of the cells has elasticity of form,

From the book Werner von Siemens - biography author Weiher Siegfried von

Transatlantic cable. Cable ship "Faraday" The obvious success of the Indo-European line, both technically and financially, should have inspired its creators to further endeavors. The opportunity to start a new business presented itself, and the inspiration turned out to be

From the book Fermat's Last Theorem by Singh Simon

Appendix 10. Example of a proof by induction In mathematics, it is important to have exact formulas, allowing you to calculate the sum of different sequences of numbers. In this case, we want to derive a formula that gives the sum of the first n natural numbers. For example, “sum” is just

From the book Faraday author Radovsky Moisey Izrailevich

From the book by Robert Williams Wood. Modern wizard of the physics laboratory by Seabrook William

From the book The Rustle of a Grenade author Prishchepenko Alexander Borisovich

CHAPTER ELEVEN Wood stretches his vacation year into three, stands where Faraday once stood, and crosses the length and breadth of our planet. An ordinary university professor is happy if he can get a free year once every seven years. But Wood doesn't

From the book of Kurchatov author Astashenkov Petr Timofeevich

From the book Travel Around the World author Forster Georg

Here it is, a discovery! A tough nut to crack Academician Ioffe and his collaborators have long been interested in the unusual behavior of crystals of Rochelle salt (double sodium salt of tartaric acid) in an electric field. This salt has so far been little studied, and there has only been

From the book Zodiac author Graysmith Robert

From the book 50 geniuses who changed the world author Ochkurova Oksana Yurievna

1 DAVID FARADAY AND BETTY LOU JENSEN Friday, December 20, 1968 David Faraday drove leisurely between the gentle hills of Vallejo, not turning special attention to the Golden Gate Bridge, to the yachts and speedboats flashing in San Pablo Bay, to the clear silhouettes of port cranes and

From the book Uncool Memory [collection] author Druyan Boris Grigorievich

Faraday Michael (b. 1791 - d. 1867) Outstanding English scientist, physicist and chemist, founder of the doctrine of the electromagnetic field, who discovered electromagnetic induction - a phenomenon that formed the basis of electrical engineering, as well as the laws of electrolysis, called his

From the book by Francis Bacon author Subbotin Alexander Leonidovich

Opening On one of the cloudy autumn days of 1965, a young man appeared in the fiction editorial office of Lenizdat with a skinny stationery folder in his hand. One could have guessed with one hundred percent probability that it contained poetry. He was clearly embarrassed and, not knowing to whom

From the book Dancing in Auschwitz by Glaser Paul

From the book Great Chemists. In 2 volumes. T.I. author Manolov Kaloyan

Discovery One of my colleagues is from Austria. We are friends, and one evening while talking he notices that the name Glaser was very common in pre-war Vienna. My father once told me, I remember, that our distant ancestors lived in the German-speaking part

From Nietzsche's book. For those who want to do everything. Aphorisms, metaphors, quotes author Sirota E. L.

MICHAEL FARADAY (1791–1867) The air in the bookbinding shop was filled with the smell of wood glue. Situated among a pile of books, the workers chatted cheerfully and diligently stitched together printed sheets. Michael was gluing up a thick volume of the Encyclopedia Britannica. He dreamed of reading it

From the author's book

Discovery of the South In the autumn of 1881, Nietzsche fell under the spell of the work of Georges Bizet - he listened to his “Carmen” in Genoa about twenty times! Georges Bizet (1838–1875) - famous French romantic composerSpring 1882 - a new journey: from Genoa by ship to Messina, about which a little

In 1821, Michael Faraday wrote in his diary: “Convert magnetism into electricity.” After 10 years, he solved this problem.
Faraday's discovery
It is no coincidence that the first and most important step in the discovery of new properties of electromagnetic interactions was taken by the founder of the concept of the electromagnetic field - Faraday.
Faraday was confident in the unified nature of electrical and magnetic phenomena. Soon after Oersted's discovery, he wrote: “... it seems very unusual that, on the one hand, every electric current is accompanied by a magnetic action of corresponding intensity, directed at right angles to the current, and that at the same time, in good conductors of electricity placed in the sphere of this action, no current was induced at all, no tangible action equivalent in strength to such a current arose. Hard work for ten years and faith in success led Faraday to a discovery that subsequently formed the basis for the design of generators for all power plants in the world, converting mechanical energy into electrical energy. (Sources operating on other principles: galvanic cells, batteries, thermal and photocells - provide an insignificant share of the generated electrical energy.)
For a long time, the relationship between electrical and magnetic phenomena could not be discovered. It was difficult to figure out the main thing: only a time-varying magnetic field can excite an electric current in a stationary coil, or the coil itself must move in a magnetic field.
“A copper wire 203 feet long was wound on a wide wooden spool, and between its turns was wound a wire of the same length, but insulated from the first with cotton thread. One of these spirals was connected to a galvanometer, and the other to a strong battery consisting of 100 pairs of plates... When the circuit was closed, a sudden but extremely weak effect on the galvanometer was noticed, and the same was noticed when the current stopped. With the continuous passage of current through one of the spirals, it was not possible to notice either an effect on the galvanometer or, in general, any inductive effect on the other spiral; 5.1
noting that the heating of the entire coil connected to the battery, and the brightness of the spark jumping between the coals, indicated the power of the battery.”
So, initially, induction was discovered in conductors that are motionless relative to each other when closing and opening a circuit. Then, clearly understanding that bringing current-carrying conductors closer or further away should lead to the same result as closing and opening a circuit, Faraday proved through experiments that current arises when the coils move relative to each other (Fig. 5.1). Familiar with the works of Ampere, Faraday understood that a magnet is a collection of small currents circulating in molecules. On October 17, as recorded in his laboratory notebook, he was found induced current in the coil while moving (or extending) the magnet (Fig. 5.2). Within one month, Faraday experimentally discovered all the essential features of the phenomenon of electromagnetic induction. All that remained was to give the law a strict quantitative form and completely reveal physical nature phenomena.
Faraday himself already grasped the general thing on which the appearance of an induction current depends in experiments that outwardly look different.
In a closed conducting circuit, a current arises when the number of magnetic induction lines penetrating the surface bounded by this circuit changes. And the faster the number of magnetic induction lines changes, the greater the current that arises. In this case, the reason for the change in the number of magnetic induction lines is completely indifferent. This may be a change in the number of lines of magnetic induction piercing a stationary conductor due to a change in the current strength in a neighboring coil, or a change in the number of lines due to the movement of the circuit in a non-uniform magnetic field, the density of the lines of which varies in space (Fig. 5.3).
Faraday not only discovered the phenomenon, but was also the first to construct an as yet imperfect model of an electric current generator that converts mechanical rotational energy into current. It was a massive copper disk rotating between the poles of a strong magnet (Fig. 5.4). By connecting the axis and edge of the disk to the galvanometer, Faraday discovered a deviation
IN
\

\
\
\
\
\
\
\L

S arrow pointing. The current was, however, weak, but the principle found made it possible to subsequently build powerful generators. Without them, electricity would still be a luxury available to few people.
An electric current arises in a conducting closed loop if the loop is in an alternating magnetic field or moves in a time-constant field so that the number of magnetic induction lines penetrating the loop changes. This phenomenon is called electromagnetic induction.

An example would be a question. In this context we can talk about taboos. There are certain areas that will be taboo for the majority, which does not mean that there will not be one, three, three scientists who will handle this phenomenon with the curiosity of a person.

These social conditions make most people uninterested in this. R: And that's just a question. The example of the fitting also shows the fear of not being discredited. Dr. Marek Spira: Today we strive to break all taboos. On the one hand, this is knowledge of the truth, and on the other, respect for certain values, the overthrow of which only leads to the destruction of social order. Human curiosity is so great that it transcends all boundaries. By nature, man does not like taboos. And in this sense, the desire for truth knows no boundaries, which exist, of course, but they are constantly moving.

A new period in the development of physical science begins with the ingenious discovery of Faraday electromagnetic induction. It was in this discovery that the ability of science to enrich technology with new ideas was clearly demonstrated. Faraday himself already foresaw, on the basis of his discovery, the existence of electromagnetic waves. On March 12, 1832, he sealed an envelope with the inscription "New Views to be kept in a sealed envelope in the archives of the Royal Society for the present time." This envelope was opened in 1938. It turned out that Faraday quite clearly understood that inductive actions propagate at a finite speed in a wave manner. “I believe it is possible to apply the theory of oscillations to the propagation of electrical induction,” wrote Faraday. At the same time, he pointed out that “the propagation of magnetic influence takes time, i.e., when a magnet acts on another distant magnet or piece of iron, the influencing cause (which I dare to call magnetism) spreads from magnetic bodies gradually and requires a certain time for its propagation , which will obviously turn out to be very insignificant. I also believe that electrical induction propagates in exactly the same way. I believe that the propagation of magnetic forces from a magnetic pole is similar to the oscillation of a disturbed surface of water or to the sound vibrations of air particles."

This raises the question of whether we will ever know the full truth. Knowing human nature we can say that although this is impossible, we will always strive for it. However, there is a danger that we will ignore this mystery. Being at a certain stage of knowledge, we can conclude that we already know everything. Meanwhile, disaster is coming, and the question is how can we let it go? Perhaps it was due to the neglect of the forces of nature, the forces of nature. An example would be the inventor of the computer, who in the last century believed that the acquisition of knowledge in a computer would be unlimited.

Faraday understood the importance of his idea and, not being able to test it experimentally, decided with the help of this envelope “to secure the discovery for himself and thus have the right, in the event experimental confirmation, declare this date as the date of its discovery." So, on March 12, 1832, humanity first came to the idea of existence electromagnetic waves. From this date the history of discovery begins radio.

Years after this discovery, with laptops today, this was a fallacy. How the extent of our ignorance has increased as the number of questions has increased. We physicists shy away from the earth. Let's say we want to fly to a galaxy several light years away from Earth. Since we cannot build a spacecraft that travels faster than the speed of light, it will not take one generation of astronauts to reach this galaxy. Although it is possible to imagine space travel for many generations of astronauts, this is only possible in science fiction.

But Faraday's discovery was important not only in the history of technology. It had a huge impact on the development of scientific understanding of the world. With this discovery, a new object enters physics - physical field. Thus, Faraday's discovery belongs to those fundamental scientific discoveries, which leave a noticeable mark on the entire history of human culture.

It is these constants, known to us today, that determine the limits of knowledge. If we consider the Big Bang, we must remember that our knowledge still does not reach the point that the density of matter is incomparable to what we are dealing with today and which we cannot reproduce in our conditions.

We don't know this "explosive" physics, so we don't know these physical constants if they existed. N.: We are also not sure that today's physics is final. We had Newton who was later tested by Einstein, so we can conclude that Einstein will be tested by someone else.

London blacksmith's son bookbinder born in London on September 22, 1791. The self-taught genius did not even have the opportunity to finish primary school and paved the way to science himself. While studying bookbinding, he read books, especially on chemistry, and performed chemical experiments himself. Listening to public lectures by the famous chemist Davy, he was finally convinced that his vocation was science, and turned to him with a request to hire him at the Royal Institution. From 1813, when Faraday was admitted to the institute as a laboratory assistant, until his death (August 25, 1867), he lived by science. Already in 1821, when Faraday received electromagnetic rotation, he set as his goal "to convert magnetism into electricity." Ten years of search and hard work culminated in the discovery of electromagnetic induction on August 29, 1871.

On this basis, the special theory of relativity was created, which has already been repeatedly confirmed experimentally. However, if one of these paradigms fails, we will have a new physics. If we say that we know the universe, nature, that we know what it was before, we say this because the indicated physical constants do not change their values over time. Experiments that try to undermine these solids- and how and how they are carried out are not convincing.

In fact, we can say that from a certain point we know that the physical laws governing the Universe have not changed - these constants are still the same. Are there secrets we don't want to face? Kant spoke of two types of metaphysics - metaphysics as a science that does not exist, and metaphysics as a natural tendency that makes us break taboos.

"Two hundred and three feet of copper wire in one piece were wound around a large wooden drum; another two hundred and three feet of the same wire was insulated in a spiral between the turns of the first winding, the metallic contact being eliminated by means of a cord. One of these spirals was connected to a galvanometer, and the other with a well-charged battery of one hundred pairs of four-inch square plates with double copper plates, when the contact was closed, there was a temporary but very weak effect on the galvanometer, and a similar weak effect took place when the contact with the battery was opened.” This is how Faraday described his first experiment on the induction of currents. He called this type of induction voltaic induction. He further describes his main experience with the iron ring - the prototype of the modern transformer.

Boundaries exist, but the human mind has natural need ask questions that cannot be answered empirically. It is not a luxury, but a person's responsibility to find it. There was once a belief that too much curiosity leaves us short of God. We ourselves have created a taboo - God cannot be known because we will lose faith. Authentic people who are respected are first and foremost trusted, and their humility was conditioned by cultural context. The educated man began to walk away from God, claiming that he would not believe in this “superstition.”

There were many misunderstandings because sometimes we did not value the search for truth. Christianity has never officially declared such a formula, because faith needs the help of reason to know the truth and even argue with the Lord God. Can we really get to know him? This is another problem, but it does not relieve us of the responsibility of constantly searching, because we have a reason. The Church today repeats that there is no contradiction between faith and reason. Even if he defeats some dogmas?

"A ring was welded from a round piece of soft iron; the thickness of the metal was seven-eighths of an inch, and the outer diameter of the ring six inches. Around one part of this ring were wound three spirals, each containing about twenty-four feet of copper wire, one twentieth of an inch thick. The spirals were insulated from the iron and from each other..., occupying approximately nine inches along the length of the ring. They could be used individually and in connection, this group is designated by the letter A. About sixty feet of the same were wound on the other part of the ring in the same way. copper wire in two pieces, which formed a spiral B, having the same direction as the spirals A, but separated from them at each end by about half an inch of bare iron.

S.: We do not need to be afraid, reason cannot cancel any dogma, and if this happens, it means that we do not need to deal with dogma, but with the human formula without covering. The reason is to destroy lies, but truth never fails. We know this from the history of the Church, even if it was very difficult, the Church was able to cleanse itself of lies, and we are proud of this.

An example of the relationship between the crew of two spaceships, after the return of the crew of one of them it was said: there is no God, and the other is so beautiful that it can only be created by God. So, if there is a taboo at all, then it is a temporary being due to cultural and social conditions, which is mainly due to the fear of dealing with something risky in terms of losing scientific position. This magic word - organization - has its origin, the question remains - what?

Helix B was connected copper wires with a galvanometer placed at a distance of three feet from the iron. The individual spirals were connected end to end so as to form a common spiral, the ends of which were connected to a battery of ten pairs of plates four inches square. The galvanometer reacted immediately, and much more strongly than was observed, as described above, using a coil ten times more powerful, but without iron; however, despite maintaining contact, the action ceased. When the contact with the battery was opened, the arrow again deflected strongly, but in the direction opposite to that which was induced in the first case."

Therefore, God knows things as they are, and we are as they are. R: You may not agree with me, but something that cannot be verified experimentally will always be more difficult to accept. Especially in the field of physics. N.: The same Kant says: I have limited knowledge in order to make room for faith. Where there are boundaries of knowledge, my faith begins.

N: The reasons for this scientist are this: all the evidence for the existence of God was false, so there is no God. Meanwhile, only the methodology is tested as follows: all evidence for the existence of God was false, but no conclusions could be drawn about his existence or his existence. And this is really beyond the scope, but there is also a huge problem here - the correct research methodology: right or wrong, this applies to every field, be it physics, astronomy, philosophy or theology.

Faraday further investigated the influence of iron by direct experiment, introducing an iron rod inside a hollow coil, in this case “the induced current had a very strong effect on the galvanometer.” "A similar effect was then obtained with the help of ordinary magnets". Faraday called this action magnetoelectric induction, assuming that the nature of voltaic and magnetoelectric induction is the same.

Why is it used to discover secrets - a natural need to advance knowledge, progress, or satisfy the subjective needs of individual researchers? This can be seen in the example of uninhibited so-called. basic research. Their nature is to discover the secrets of nature, regardless of the frequent stimulus for their immediate use. When Faraday discovered the phenomenon of electromagnetic induction, he was asked what it would be like to have humanity?

He said evasively that you will probably pay taxes and not address the scientific side of the discovery. His subjective need was the desire to know and the satisfaction that came from it. It seems to me that exploiting the usefulness of the study is not justified.

All the experiments described constitute the content of the first and second sections of Faraday’s classic work “Experimental Research in Electricity,” begun on November 24, 1831. In the third section of this series, “On the New Electric State of Matter,” Faraday for the first time tries to describe the new properties of bodies manifested in electromagnetic induction. He calls this property he discovered the “electrotonic state.” This is the first germ of the field idea, which was later formed by Faraday and first precisely formulated by Maxwell. The fourth section of the first series is devoted to the explanation of the Arago phenomenon. Faraday correctly classifies this phenomenon as induction and tries to use this phenomenon to “obtain a new source of electricity.” By moving a copper disk between the poles of a magnet, it received a current in the galvanometer using sliding contacts. This was the first Dynamo machine. Faraday summarizes the results of his experiments in the following words: “It was thus shown that a constant current of electricity could be created by means of an ordinary magnet.” From his experiments on induction in moving conductors, Faraday derived the relationship between the pole of a magnet, the moving conductor and the direction of the induced current, i.e., “the law governing the production of electricity through magnetoelectric induction.” As a result of his research, Faraday established that “the ability to induce currents is manifested in a circle around the magnetic resultant or force axis in exactly the same way as magnetism located around a circle arises around an electric current and is detected by it” *.

Let the university in basic research continue to ask questions about why and discover new laws or rules, and colleges technical use should use them to make life easier, more convenient, more interesting, attractive, etc. transferring this unit incorrectly will not bring any benefit. S.: The search for truth is selfless. The child raises thousands of questions, and the parents answer them. When Columbus set out to travel around the world, he was asked why he was going there.

For the whole world was created. But he needed to know for himself. He kills us with the assertion that everything must be useful. For in this case truth is interpreted instrumentally, knowing that mystery also plays an important role. The question of the meaning of human life is becoming completely useless in our culture. But, on the other hand, if we did not ask this question, our life would be meaningless. First, there is selflessness, and then it may turn out that the truth is used in different ways for the benefit of personal, social, economic, political life.

* (M. Faraday, Experimental Research in Electricity, Vol. I, Ed. USSR Academy of Sciences, 1947, p. 57.)

In other words, a vortex appears around the alternating magnetic flux electric field, just as a vortex magnetic field arises around an electric current. This fundamental fact was summarized by Maxwell in the form of his two electromagnetic field equations.

For every opening you need to be well prepared. Each discovery, even the so-called media catastrophe, is covered by the vast knowledge and experience of the researcher. Only great knowledge, imagination and going beyond the traditional framework of scientific research allows us to see something new, new, unknown, and then called discovery. Copernicus was condemned not because he did not like him, for example, he was from Toruń, but because he could not understand that the Bible cannot be read literally. Often the researcher is faced with a vulgar approach to learning, knowledge and misunderstanding.

The second series of “Research”, begun on January 12, 1832, is also devoted to the study of the phenomena of electromagnetic induction, especially the inductive action of the Earth’s magnetic field. Faraday devotes the third series, begun on January 10, 1833, to proving the identity of various types of electricity: electrostatic, galvanic, animal , magnetoelectric (i.e., obtained through electromagnetic induction). Faraday comes to the conclusion that the electricity produced different ways, are qualitatively the same, the difference in actions is only quantitative. This dealt the final blow to the concept of various “fluids” of resin and glass electricity, galvanism, animal electricity. Electricity turned out to be a single, but polar entity.

Sometimes the discoverer is ahead of his time, only a new generation accepts his discovery. We also today have a natural tendency to comfortably fit the world into different sides, so we don't have to think just to consume. An example is James Clerk Maxwell, whose famous equation is our civilization; Without them, it would be difficult to imagine today's successes and development. However, Maxwell's understanding of the mechanism of electromagnetic propagation does not fit into today's interpretation of this phenomenon.

In addition, Olivier Heaviside, another scientist and mathematician, made his mathematical and mathematical formulas very useful. This is an example of the essence and type of continuity of science: many scientists, even the “smallest,” contribute to universal knowledge. Isn’t this comforting in an era of yet another humiliation in the academic world? What are the secrets of modern science facing the greatest research opportunities?

The fifth series of Faraday's Researches, begun on June 18, 1833, is very important. Here Faraday begins his research on electrolysis, which led him to the establishment of the famous laws that bear his name. These studies were continued in the seventh series, begun on January 9, 1834. In this last series, Faraday proposes new terminology: he proposes to call the poles that supply current to the electrolyte electrodes, call positive electrode anode, and negative - cathode, particles of deposited substance going to the anode he calls anions, and the particles going to the cathode are cations. Further, he owns the terms electrolyte for degradable substances, ions And electrochemical equivalents. All these terms are firmly established in science. Faraday draws the correct conclusion from the laws he found that we can talk about some absolute quantity electricity associated with atoms of ordinary matter. “Although we know nothing about what an atom is,” writes Faraday, “we involuntarily imagine some small particle that appears to our mind when we think about it; however, in the same or even greater ignorance we are in relation to electricity, we are not even able to say whether it represents a special matter or matter, or simply the movement of ordinary matter, or another type of force or agent; nevertheless, there is a huge number of facts that make us think, that the atoms of matter are in some way endowed with or connected with electrical forces, and to them they owe their most remarkable qualities, including their chemical affinity for each other."

Scientists still wonder why the charge of a proton is positive and the electron is negative? What properties does antimatter have? How does a material known for very high temperatures? These questions really matter. We are talking about temperatures comparable to the internal temperature of the Sun. This is a huge problem for physicists, very important in the context of the search for new energy sources.

To illustrate the importance of this problem for humanity, it is enough to give one of the estimates. In a situation of such great progress in science, in the use of nature in the service of humanity, the problem remains of man, who is becoming more and more confused. The changes are starting to blur. The unknown development of science does not have a negative impact on the intellectual development of societies, but on the contrary - negative phenomena, such as secondary illiteracy, are multiplying.

* (M. Faraday, Experimental Research in Electricity, Vol. I, Ed. USSR Academy of Sciences, 1947, p. 335.)

Thus, Faraday clearly expressed the idea of "electrification" of matter, atomic structure electricity, and the atom of electricity, or, as Faraday puts it, “the absolute quantity of electricity,” turns out to be "just as definite in its action, like any of those quantities which, remaining connected with the particles of matter, impart to them their chemical affinity." Elementary electric charge, as shown further development physics, can indeed be determined from Faraday's laws.

The ninth series of Faraday's Studies was very important. This series, begun on December 18, 1834, dealt with the phenomena of self-induction, with extra currents of closure and opening. Faraday points out when describing these phenomena that although they have features inertia, However, the phenomenon of self-induction is distinguished from mechanical inertia by the fact that they depend on forms conductor. Faraday notes that “extract is identical with ... induced current” *. As a result, Faraday developed an idea of the very broad significance of the induction process. In the eleventh series of his studies, begun on November 30, 1837, he states: “Induction plays the most general role in all electrical phenomena, participating, apparently, in each of them, and in fact bears the features of the first and essential principle” ** . In particular, according to Faraday, every charging process is an induction process, offsets opposite charges: “substances cannot be charged absolutely, but only relatively, according to the law identical with induction. Every charge is maintained by induction. All phenomena voltage include the beginning of inductions" ***. The meaning of these statements by Faraday is that any electric field ("voltage phenomenon" - in Faraday's terminology) is necessarily accompanied by an induction process in the medium ("displacement" - in Maxwell's later terminology). This process is determined by the properties of the medium , its “inductive ability”, in Faraday’s terminology, or “dielectric constant”, in modern terminology. Faraday’s experiments with a spherical capacitor determined the dielectric constant of a number of substances with respect to air. These experiments strengthened Faraday’s idea of the essential role of the medium in electromagnetic processes.

* (M. Faraday, Experimental Research in Electricity, Vol. I, Ed. USSR Academy of Sciences, 1947, p. 445.)

** (M. Faraday, Experimental Research in Electricity, Vol. I, Ed. USSR Academy of Sciences, 1947, p. 478.)

*** (M. Faraday, Experimental Research in Electricity, Vol. I, Ed. USSR Academy of Sciences, 1947, p. 487.)

The law of electromagnetic induction was significantly developed by a Russian physicist of the St. Petersburg Academy Emilie Christianovich Lentz(1804-1865). On November 29, 1833, Lenz reported to the Academy of Sciences his research “On determining the direction of galvanic currents excited by electrodynamic induction.” Lenz showed that Faraday's magnetoelectric induction is closely related to Ampere's electromagnetic forces. “The position by which the magnetoelectric phenomenon is reduced to the electromagnetic one is as follows: if a metal conductor moves close to a galvanic current or magnet, then a galvanic current is excited in it in such a direction that if the conductor were stationary, the current could cause it to move in the opposite direction; it is assumed that a conductor at rest can move only in the direction of movement or in the opposite direction" *.

* (E. H. Lenz, Selected Works, Ed. Academy of Sciences of the USSR, 1950, pp. 148-149.)

This Lenz principle reveals the energetics of induction processes and played an important role in Helmholtz’s work on establishing the law of conservation of energy. Lenz himself derived from his rule the well-known principle in electrical engineering of the reversibility of electromagnetic machines: if you rotate a coil between the poles of a magnet, it generates a current; on the contrary, if a current is sent into it, it will rotate. An electric motor can be turned into a generator and vice versa. While studying the action of magnetoelectric machines, Lenz discovered the armature reaction in 1847.

In 1842-1843 Lenz produced a classic study “On the laws of heat release by galvanic current” (reported on December 2, 1842, published in 1843), which he began long before Joule’s similar experiments (Joule’s report appeared in October 1841) and continued by him despite the publication Joule, “since the latter’s experiments may meet with some justified objections, as has already been shown by our colleague Mr. Academician Hess” *. Lenz measures the magnitude of the current using a tangent compass, a device invented by Helsingfors professor Johann Nervander (1805-1848), and in the first part of his message examines this device. In the second part, “Heat Release in Wires,” reported on August 11, 1843, he comes to his famous law:

Heating of the wire by galvanic current is proportional to the resistance of the wire.
Heating of a wire by galvanic current is proportional to the square of the current used for heating"**.

* (E. H. Lenz, Selected Works, Ed. USSR Academy of Sciences, 1950, p. 361.)

** (E. H. Lenz, Selected Works, Ed. USSR Academy of Sciences, 1950, p. 441.)

The Joule-Lenz law played an important role in establishing the law of conservation of energy. The entire development of the science of electrical and magnetic phenomena led to the idea of the unity of the forces of nature, to the idea of preserving these “forces”.

Almost simultaneously with Faraday, electromagnetic induction was observed by an American physicist Joseph Henry(1797-1878). Henry made a large electromagnet (1828) which, powered by a low-resistance galvanic cell, supported a load of 2,000 pounds. Faraday mentions this electromagnet and points out that with its help you can get a strong spark when opened.

Henry was the first to observe the phenomenon of self-induction (1832), and his priority is marked by the name of the unit of self-induction “Henry”.

In 1842 Henry established oscillatory character Leyden jar type. The thin glass needle with which he studied this phenomenon was magnetized with different polarities, while the direction of the discharge remained unchanged. “The discharge, whatever its nature,” Henry concludes, “does not seem (using Franklin’s theory. - P.K.) to be a single transfer of weightless fluid from one plate to another; the discovered phenomenon forces us to assume the existence of a main discharge in one direction, and then several strange movements back and forth, each weaker than the last, continuing until equilibrium is achieved."

Induction phenomena are becoming a leading topic in physical research. In 1845, a German physicist Franz Neumann(1798-1895) gave mathematical expression law of induction, summarizing the research of Faraday and Lenz.

The electromotive force of induction was expressed by Neumann in the form of a time derivative of some function inducing the current and the mutual configuration of interacting currents. Neumann called this function electrodynamic potential. He also found an expression for the coefficient of mutual induction. In his essay “On the Conservation of Force” in 1847, Helmholtz derived Neumann’s expression for the law of electromagnetic induction from energy considerations. In the same work, Helmholtz states that the discharge of a capacitor is “not... a simple movement of electricity in one direction, but... its flow in one direction or the other between two plates in the form of oscillations that become less and less less, until finally all living force is destroyed by the sum of resistances."

In 1853 William Thomson(1824-1907) gave a mathematical theory of the oscillatory discharge of a capacitor and established the dependence of the oscillation period on the parameters of the oscillatory circuit (Thomson's formula).

In 1858 P. Blazerna(1836-1918) experimentally recorded the resonant curve of electrical oscillations, studying the effect of a discharge-inducing circuit containing a bank of capacitors and connecting conductors to a side circuit, with a variable length of the induced conductor. Also in 1858 Wilhelm Feddersen(1832-1918) observed the spark discharge of a Leyden jar in a rotating mirror, and in 1862 he photographed an image of a spark discharge in a rotating mirror. Thus, the oscillatory nature of the discharge was clearly established. At the same time, Thomson's formula was tested experimentally. Thus, step by step, the doctrine of electrical vibrations, constituting the scientific foundation of alternating current electrical engineering and radio engineering.

After the discoveries of Oersted and Ampere, it became clear that electricity has magnetic force. Now it was necessary to confirm the influence of magnetic phenomena on electrical ones. Faraday brilliantly solved this problem.

Michael Faraday (1791-1867) was born in London, in one of its poorest parts. His father was a blacksmith, and his mother was the daughter of a tenant farmer. When Faraday reached school age, he was sent to primary school. The course Faraday took here was very narrow and was limited only to learning to read, write and begin to count.

A few steps from the house in which the Faraday family lived, there was a bookshop, which was also a bookbinding establishment. This is where Faraday ended up, having completed his primary school course, when the question arose about choosing a profession for him. Michael was only 13 years old at this time.

Already in his youth, when Faraday was just beginning his self-education, he sought to rely exclusively on facts and verify the messages of others with his own experiences. These aspirations dominated him all his life as the main features of his scientific activity.

Faraday began to carry out physical and chemical experiments as a boy at his first acquaintance with physics and chemistry. One day Michael attended one of the lectures of Humphry Davy, the great English physicist. Faraday made a detailed note of the lecture, bound it and sent it to Davy. He was so impressed that he invited Faraday to work with him as a secretary. Soon Davy went on a trip to Europe and took Faraday with him. Over the course of two years, they visited the largest European universities.

Based on the experiences of his predecessors and combining several of his own experiences, by September 1821 Michael published “The History of the Advances of Electromagnetism.” Already at this time, he formed a completely correct concept of the essence of the phenomenon of deflection of a magnetic needle under the influence of current. Having achieved this success, Faraday left his studies in the field of electricity for ten years, devoting himself to the study of a number of subjects of a different kind.

In 1823, Faraday made one of the most important discoveries in the field of physics - he was the first to liquefy gas, and at the same time established a simple but effective method for converting gases into liquid.

In 1824, Faraday made several discoveries in the field of physics. Among other things, he established the fact that light affects the color of glass, changing it.

The following year, Faraday again turned from physics to chemistry, and the result of his work in this area was the discovery of gasoline and sulfur-naphthalene acid.

In 1831, Faraday published a treatise on “A Special Kind of Optical Illusion,” which served as the basis for an excellent and curious optical projectile called the “chromotrope.” In the same year, another treatise by the scientist, “On Vibrating Plates,” was published.

Many of these works could themselves immortalize the name of their author. But the most important of Faraday's scientific works are his studies in the field of electromagnetism and electrical induction. Strictly speaking, an important branch of physics that treats the phenomena of electromagnetism and inductive electricity, and which is currently of such enormous importance for technology, was created by Faraday out of nothing.

At the same time, it was known that a wire through which current passes and which also represents an electrified body does not have any effect on other wires placed nearby. What caused this exception? This is the question that interested Faraday and the solution of which led him to the most important discoveries in the field of induction electricity.

As was his custom, Faraday began a series of experiments designed to clarify the essence of the matter. Faraday wound two insulated wires parallel to each other on the same wooden rolling pin. He connected the ends of one wire to a battery of ten cells, and the ends of the other to a sensitive galvanometer. When a current was passed through the first wire, Faraday turned all his attention to the galvanometer, expecting to notice by its vibrations the appearance of a current in the second wire. However, nothing of the kind happened: the galvanometer remained calm. Faraday decided to increase the current strength and introduced 120 galvanic elements into the circuit. The result was the same. Faraday repeated this experiment dozens of times and still with the same success. Anyone else in his place would have left the experiments convinced that the current passing through a wire has no effect on the neighboring wire. But Faraday always tried to extract from his experiments and observations everything that they could give, and therefore, not receiving a direct effect on the wire connected to the galvanometer, he began to look for side effects.

He immediately noticed that the galvanometer, remaining completely calm during the entire passage of current, began to oscillate when the circuit itself was closed and when it was opened. It turned out that at the moment when a current is passed into the first wire, and also when this transmission stops, a current is also excited in the second wire, which in the first case has the opposite direction to the first current and the same with it in the second case and lasts only one instant. Secondary instantaneous currents caused by the influence of primary ones were called inductive by Faraday, and this name has remained with them to this day.

Being instantaneous, instantly disappearing after their appearance, inductive currents would have no practical significance if Faraday had not found a way, with the help of an ingenious device (a commutator), to constantly interrupt and re-conduct the primary current coming from the battery along the first wire, thanks to which the second wire is continuously excited by more and more new inductive currents, thus becoming constant. Thus, a new source of electrical energy was found, in addition to the previously known ones (friction and chemical processes), - induction, and a new type of this energy - inductive electricity.

These discoveries in turn gave rise to new ones. If it is possible to cause an inductive current by short-circuiting and stopping the galvanic current, then wouldn’t the same result be obtained by magnetizing and demagnetizing iron? The work of Oersted and Ampere had already established the relationship between magnetism and electricity. It was known that iron becomes a magnet when an insulated wire is wound around it and a galvanic current passes through it, and that the magnetic properties of this iron cease as soon as the current stops. Based on this, Faraday came up with this kind of experiment: two insulated wires were wound around an iron ring; with one wire wrapped around one half of the ring, and the other around the other.

Current from a galvanic battery was passed through one wire, and the ends of the other were connected to a galvanometer. And so, when the current closed or stopped and when, consequently, the iron ring was magnetized or demagnetized, the galvanometer needle quickly oscillated and then quickly stopped, that is, the same instantaneous inductive currents were excited in the neutral wire - this time: already under the influence of magnetism. Thus, here for the first time magnetism was converted into electricity.

Having received these results, Faraday decided to diversify his experiments. Instead of an iron ring, he began to use an iron strip. Instead of exciting magnetism in iron by galvanic current, he magnetized the iron by touching it to a permanent steel magnet. The result was the same: always in the wire wrapped around the iron! a current was excited at the moment of magnetization and demagnetization of iron. Then Faraday introduced a steel magnet into the wire spiral - the approach and removal of the latter caused induced currents in the wire. In a word, magnetism, in the sense of exciting induction currents, acted in exactly the same way as galvanic current.

At that time, physicists were intensely interested in one mysterious phenomenon, discovered in 1824 by Arago and which could not be explained, despite; the fact that this explanation was intensely sought by such outstanding scientists of the time as Arago himself, Ampère, Poisson, Babage and Herschel. Case I was as follows. A magnetic needle, hanging freely, quickly comes to rest if a circle of non-magnetic metal is placed under it; If the circle is then put into rotation, the magnetic needle begins to move behind it. In a calm state, it was impossible to discover the slightest attraction or repulsion between the 5th circle and the arrow, while the same circle, in motion, pulled behind it not only a light arrow, but also a heavy magnet. This truly miraculous phenomenon seemed to the scientists of that time a mysterious mystery, something beyond the limits of the natural. Faraday, based on the above data, made the assumption that a circle of non-magnetic metal, under the influence of a magnet, during rotation is run around by inductive currents, which affect the magnetic needle and drag it along the magnet. And indeed, by introducing the edge of a circle between the poles of a large horseshoe magnet and connecting the center and edge of the circle with a galvanometer with a wire, Faraday obtained a constant electric current when the circle rotated.

Following this, Faraday focused on another phenomenon that was then arousing general curiosity. As you know, if you sprinkle iron filings on a magnet, they group along certain lines called magnetic curves. Faraday, drawing attention to this phenomenon, gave magnetic curves the name “lines of magnetic force” in 1831, which later came into general use. The study of these “lines” led Faraday to a new discovery; it turned out that in order to excite induced currents, the source’s approach and distance from the magnetic pole are not necessary. To excite currents, it is enough to cross the lines of magnetic force in a known manner.

Further work Faraday's efforts in the mentioned direction acquired, from a contemporary point of view, the character of something absolutely miraculous. At the beginning of 1832, he demonstrated a device in which inductive currents were excited without the help of a magnet or galvanic current.

The device consisted of an iron strip placed in a wire coil.

This device, under ordinary conditions, did not give the slightest sign of the appearance of currents in it; but as soon as it was given a direction corresponding to the direction of the magnetic needle, a current was excited in the wire. Then Faraday gave the position of the magnetic needle to one coil and then introduced an iron strip into it: the current was again excited. The reason that caused the current in these cases was earthly magnetism, which caused inductive currents like an ordinary magnet or galvanic current. To more clearly show and prove this, Faraday undertook another experiment, which fully confirmed his considerations. He reasoned that if a circle of non-magnetic metal, such as copper, rotating in a position in which it intersects the lines of magnetic force of an adjacent magnet, produces an inductive current, then the same circle, rotating in the absence of a magnet, but in a position in which the circle will cross the lines of earthly magnetism, must also give an inductive current. And indeed, a copper circle rotated in a horizontal plane produced an inductive current that produced a noticeable deflection of the galvanometer needle.

Faraday ended his series of studies in the field of electrical induction with the discovery, made in 1835, of the “inductive influence of current on itself.” He found out that when a galvanic current is closed or opened, instantaneous inductive currents are excited in the wire itself, which serves as a conductor for this current.

Russian physicist Emil Khristoforovich Lenz (1804-1861) gave a rule for determining the direction of induction current.

“The induction current is always directed in such a way that the magnetic field it creates complicates or inhibits the movement causing induction,” notes A.A. Korobko-Stefanov in his article on electromagnetic induction. - For example, when a coil approaches a magnet, the resulting induced current has such a direction that the magnetic field it creates will be opposite to the magnetic field of the magnet. As a result, repulsive forces arise between the coil and the magnet.

Lenz's rule follows from the law of conservation and transformation of energy. If induced currents accelerated the motion that caused them, then work would be created out of nothing. The coil itself, after a slight push, would rush towards the magnet, and at the same time the induction current would release heat in it. In reality, the induced current is created due to the work of bringing the magnet and the coil closer together.

Why does induced current occur? A deep explanation of the phenomenon of electromagnetic induction was given by the English physicist James Clerk Maxwell, the creator of a complete mathematical theory electromagnetic field.

To better understand the essence of the matter, consider a very simple experiment. Let the coil consist of one turn of wire and be penetrated by an alternating magnetic field perpendicular to the plane of the turn. An induced current naturally arises in the coil. Maxwell interpreted this experiment exceptionally boldly and unexpectedly. When a magnetic field changes in space, according to Maxwell, a process arises for which the presence of a wire coil has no significance. The main thing here is the emergence of closed annular electric field lines, covering a changing magnetic field.

Under the influence of the resulting electric field, electrons begin to move, and an electric current arises in the coil. A coil is simply a device that detects an electric field. The essence of the phenomenon of electromagnetic induction is that an alternating magnetic field always generates an electric field with closed circuits in the surrounding space power lines. Such a field is called a vortex field.”

Research in the field of induction produced by terrestrial magnetism gave Faraday the opportunity to express the idea of a telegraph back in 1832, which then formed the basis of this invention.

In general, the discovery of electromagnetic induction is not without reason considered one of the most outstanding discoveries of the 19th century - the work of millions of electric motors and electric current generators all over the world is based on this phenomenon...

The phenomenon of electromagnetic induction was discovered by Mile Faraday in 1831. Even 10 years earlier, Faraday was thinking about a way to turn magnetism into electricity. He believed that the magnetic field and the electric field must be somehow connected.

Discovery of electromagnetic induction

For example, using an electric field you can magnetize iron object. It should probably be possible to generate electric current using a magnet.

First, Faraday discovered the phenomenon of electromagnetic induction in conductors that are motionless relative to each other. When a current appeared in one of them, a current was also induced in the other coil. Moreover, in the future it disappeared, and appeared again only when the power to one coil was turned off.

After some time, Faraday proved through experiments that when a coil without current moves in a circuit relative to another, the ends of which are supplied with voltage, an electric current will also arise in the first coil.

The next experiment was the introduction of a magnet into the coil, and at the same time a current appeared in it. These experiments are shown in the following figures.

Faraday formulated the main reason for the appearance of current in a closed circuit. In a closed conducting circuit, current arises when the number of magnetic induction lines that penetrate this circuit changes.

The greater this change, the stronger the induced current. It does not matter how we achieve a change in the number of magnetic induction lines. For example, this can be done by moving a circuit in a non-uniform magnetic field, as happened in the experiment with a magnet or moving a coil. And we can, for example, change the current strength in a coil adjacent to the circuit, and the magnetic field created by this coil will change.

Statement of the law

Let's sum it up summary. The phenomenon of electromagnetic induction is the phenomenon of the occurrence of current in a closed circuit, when the magnetic field in which this circuit is located changes.

For a more precise formulation of the law of electromagnetic induction, it is necessary to introduce a quantity that would characterize the magnetic field - the flux of the magnetic induction vector.

Magnetic flux

The magnetic induction vector is designated by the letter B. It will characterize the magnetic field at any point in space. Now consider a closed contour bounding a surface of area S. Let us place it in a uniform magnetic field.

There will be a certain angle a between the normal vector to the surface and the magnetic induction vector. Magnetic fluxФ through a surface of area S is called physical quantity, equal to the product of the magnitude of the magnetic induction vector by the surface area and the cosine of the angle between the magnetic induction vector and the normal to the contour.

Ф = B*S*cos(a).

The product B*cos(a) is the projection of the vector B onto the normal n. Therefore, the form for magnetic flux can be rewritten as follows:

The unit of magnetic flux is the weber. Indicated by 1 Wb. A magnetic flux of 1 Wb is created by a magnetic field with an induction of 1 T through a surface area of 1 m^2, which is located perpendicular to the magnetic induction vector.