Today we will talk about the experience of Faraday, an English physicist, and the importance of electromagnetic induction in the modern world.
Sun, lightning, volcano
Ancient people worshiped the incomprehensible. We are talking about the times when the most advanced invention was the ability to combine a stick and a stone into the simplest tool. There was no explanation for the daily course of the Sun, the phases of the Moon, volcanoes, the occurrence of lightning and thunder.
With thunderstorms, mankind has a separate novel. Fire dispelled darkness, gave a sense of security, inspired discoveries. And scientists suggest that the first controlled fire was created from wood set on fire by lightning.
Hammer and Magnet
A little later, people learned to use heat to melt metal. The first strong tools appeared that helped to conquer the surrounding nature. Going exclusively by experiment, different masters probably stumbled upon unusual and strange incidents. For example, one piece of iron could suddenly move in the presence of another (magnetism). In the nineteenth century, these phenomena were explained by the experiments of Faraday (electromagnetic induction in the modern sense arose precisely then).
Science andkings
Electric current has been known for a long time. They knew how to distinguish iron from glass by the property of conducting electrons in the time of Michelangelo. But until the beginning of the nineteenth century, this phenomenon was considered exclusively as a funny phenomenon. In addition, scientists have always been sponsored by a we althy philanthropist - a count, duke or king. And the money invested, as you know, should have paid off. So physicists and chemists needed to work in such a way that the military power of the nobleman increased, he received more profit or enjoyed a bright spectacle.
Some experiments were shown to the guests as a sign of the power of the owner of the money. Galileo named the moons of Jupiter he discovered in honor of his patron, the Medici. So it was with electricity. Faraday's experiments confirmed electromagnetic induction experimentally. But before him, there were Oersted's studies.
Electric or magnetic?
The magnet (the main part of the compass) was used by sailors who discovered America, Australia and the way to India. Electricity was interesting fun. In 1820, the Danish scientist Hans Christian Oersted proved the connection between the magnetic and electrical properties of conductors. His experiment was the forerunner of Faraday's experiment, the phenomenon of electromagnetic induction and everything that followed from the discoveries of those years.
So, Oersted took a linear conductor (thick wire) and placed a magnetic needle under it. When the scientist started the current, the poles of the magnet shifted: the arrow stood perpendicular to the conductor. The physicist repeated the experiment many times,changed the geometry of the experiment and the direction of the current in the conductor. The result was the same: the location of the poles of the magnetic needle was always the same with respect to the vector of motion of the electrons. Now this experience seems very simple and understandable. But the discovery had far-reaching consequences: Oersted proved the direct relationship between electric and magnetic fields.
Property relationship
But if the electric current was able to affect the magnet, then the magnet could cause the electrons to move? This is what Faraday tried to prove by the experiment, the description of which we will now give.
The scientist wound the wire into a spiral (coil), connected a current-detecting device to it and brought a magnet to the structure. The meter needle flickered. The experience turned out to be successful. In the future, Michael Faraday applied various approaches and found out: if instead of a magnet we take one coil and excite a current in it, then a current will also appear in the adjacent coil. The interaction is even more effective when a conductive core is inserted inside the turns of both helices.
Law of electromagnetic induction
Faraday's law of induction for a closed circuit is expressed by the formula: ε=-dΦ / dt.
Here ε is the electromotive force that causes the electrons to move in the conductor (abbreviated as EMF), Φ is the magnitude of the magnetic flux that is currently passing through a given area, and t is the time.
This formula is differential. This means that the EMF should be calculated for all small periods of time using small pieces of area. BUTto get the total electromotive force, the result must be summed.
The minus in the formula is due to Lenz's rule. It reads: The induction emf is directed so that the excited current blocks the change in flow direction.
It is quite easy to explain this rule with an example: when the current in the first coil increases, the current in the second one will also increase; when the current in the first coil decreases, the induced one will also weaken.
Applying Faraday's Law
Modern life is unimaginable without electricity. In The Day the Earth Stood Still, Keanu Reeves' character changes the course of human history by turning off the generators. We will not talk about the mechanisms of this incident now. Fiction gives free rein to the imagination, but does not describe the possibilities. But the consequences of such a phenomenon would be truly global: from the destruction of urban infrastructure to famine. People would actually have to rebuild their civilization to adapt to an existence without electricity.
Many science fiction authors exploit the plot of a global catastrophe. In addition to the power cut, the reasons for such a major change are:
- foreign invasion;
- wrong bacteriological experiment;
- accidental discovery of a physical law that changes the structure of matter (for example, ice-9);
- nuclear war or catastrophe;
- an evolutionary leap of people (the new humanity simply does not need technology).
Search for energy sources isseparate area of human activity. People use the energy of fossil resources, water, wind, waves, the heat of underground thermal waters and the atom to get electricity. All stations work thanks to the principle, the existence of which was proved by Faraday in his experiments. Moreover, the scheme for generating electricity is not too different from his experiment: a certain force rotates a huge magnet (rotor), and that, in turn, excites current in the coils.
Of course, people found an excellent material for cores, learned how to make huge spools, isolate winding layers from each other much better. But in general, modern civilization stands on the experience produced by Michael Faraday in August 1831.
