The discovery of electromagnetic induction

After the discoveries of Oersted and Ampere, it became clear that electricity has a magnetic force. Now it was necessary to confirm the influence of magnetic phenomena on electrical phenomena. This task brilliantly decided Faraday.

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

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

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

Faraday made a detailed lecture record, interlaced it and sent Davy away. He was so impressed that he offered Faraday to work with him as a secretary. Soon Davy went on a trip to Europe and took Faraday with him. For 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 Institute in London. At that time it was one of the best physical laboratories in the world. From 1816 to 1818 Faraday printed a series of small notes and small memoirs on chemistry. By 1818, the first work of Faraday in physics.

Drawing on the experiences of his predecessors and combining several of his own experiments, by September 1821, Michael published the "History of the Successes of Electromagnetism . " Already at this time he made quite the correct concept of the essence of the phenomenon of the deviation of the magnetic needle under the action of current.

Achieving this success, Faraday for ten years left the occupation in the field of electricity, devoting himself to the study of a number of other subjects. In 1823 Faraday made one of the most important discoveries in the field of physics - he first achieved liquefaction of gas, and at the same time established a simple but valid method of 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 the glass, changing it. The next year, Faraday again turns from physics to chemistry, and the result of his work in this area is the discovery of gasoline and sulfuric-naphthalic acid.

In 1831, Faraday published a treatise "On a special kind of optical illusion", which served as the basis for a beautiful and curious optical projectile, called "chromotrope." In the same year, another treatise of 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 department of physics, dealing with the phenomena of electromagnetism and induction electricity, and which currently has such tremendous importance for technology, was created by Faraday from nothing.

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

Why did this exception depend? Here is the question that interested Faraday and whose solution led him to the most important discoveries in the field of induction electricity. As usual, Faraday began a series of experiments that were to clarify the essence of the matter.

Faraday wound two parallel wires to the same wooden rolling pin. The ends of one wire he connected with a battery of ten elements, and the ends of the other - with a sensitive galvanometer. When the current was passed through the first wire,

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

Anyone else in his place would leave the experiments convinced that the current passing through the wire does not have any effect on the neighboring wire. But Faraday always tried to extract from his experiments and observations everything that they can give, and therefore, not having received direct action on the wire, connected with the galvanometer, began to look for side effects.

Immediately he noticed that the galvanometer, while remaining completely calm during the passage of the current, comes to oscillation at the very closing of the circuit and when it opens. It turned out that at the moment when the current is passed into the first wire, and also when this transmission ceases, in The second wire is also excited with a current having in the first case an opposite direction with the first current and the same with it in the second case and lasting only one instant.

These secondary instantaneous currents, caused by the influence of primary, were called Faraday inductive, and this name has been preserved for them hitherto. Being instantaneous, instantly disappearing after their appearance, inductive currents would not have any practical significance if Faraday did not find a way with an ingenious device (switch) to continually interrupt and again conduct the primary current coming from the battery through the first wire, The second wire continually raises more and more inductive currents, thus becoming permanent. So a new source of electrical energy was found, in addition to the previously known (friction and chemical processes) - induction, and a new kind of this energy - induction electricity .

Continuing his experiments, Faraday went on to say that a simple approximation of a wire twisted into a closed curve is sufficient, to the next one, along which a galvanic current flows, in order to excite in the neutral wire an inductive current of the direction opposite to the galvanic current, that the removal of the neutral wire again excites the inductive The current is already the same direction with the galvanic going through the fixed wire, and that, finally, these inductive currents are excited only during the approach and removal of the wire to the galvanic current conductor, and without this motion, the currents are not excited, no matter how closely the wires are to each other .

Thus, a new phenomenon was discovered, similar to the above-described phenomenon of induction when the galvanic current is closed and stopped. In turn, these discoveries caused new ones. If it is possible to cause an inductive current by closing and stopping the galvanic current, will the same result result from magnetization and demagnetization of the iron?

The works of Oersted and Ampere have already established the relationship of magnetism and electricity. It was known that iron is made by a magnet when an insulated wire is wound around it and the galvanic current passes through it and that the magnetic properties of this iron cease as soon as the current ceases.

Proceeding from this, Faraday came up with this kind of experience: two insulated wires were wound around the iron ring; One wire was wound around one half of the ring, and the other around the other. A current from the 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 arrow of the galvanometer rapidly oscillated and then quickly stopped, that is, in the neutral wire, the same instantaneous inductive currents were excited-this time: already under the influence of magnetism.

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

Faraday then introduced a steel magnet into the wire helix - the approximation and removal of the latter caused induction currents in the wire. In a word, magnetism, in the sense of excitation of induction currents, acted quite the same as the galvanic current.

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