The basis of modern electrical engineering is the phenomenon of electromagnetic induction

The phenomenon of electromagnetic induction in electrical engineering is one of the basic. It was an experimental way discovered in the distant 1831 by the English physicist Michael Faraday. At that time, it was known that interaction between a conductor with a current and a nearby magnet occurs. It was believed that stationary charges interact through an electric field, and their motion (current) is manifested through a magnetic field. However, the prospect of practical use of this knowledge to the results of the Faraday experiment was very vague. In fact, the scientist, having discovered the phenomenon of electromagnetic induction, laid the foundations of modern electrical engineering.

The experience itself was quite simple: a bar of a permanent magnet moved in and moved out into the central space between the turns of the coil. The coil leads were connected to a sensitive device for measuring low current and voltage values.

It was noted that when the magnet moves, the galvanometer needle deviates from the zero point. And the deviation was the more, the more the magnet moved. If we recall that it has two poles and lines of field strength, then the relationship between the magnetic flux and the induction current is evident.

Since spontaneous current can not arise in the circuit, a logical conclusion was made about the appearance of electromotive force (EMF), which, in turn, allows the appearance of a current. Faraday's law of electromagnetic induction allows us to state that the influence of a magnetic field that varies over time causes the appearance of a changing electric field and, in the presence of a closed circuit, a current.

The phenomenon of electromagnetic induction allowed the scientist to make a revolutionary conclusion: the cause of the electric field can be not only charges, but also a changing magnetic field. Later, he formulated a generalization. Thus, Faraday's law for electromagnetic induction says: the emf created by the magnetic field is directly dependent on the rate of change of the magnetic flux. The generated current for a closed loop is calculated according to Ohm's law.

The phenomenon of electromagnetic induction is characteristic not only of conductors, but also of massive conductive bodies. Thus, a changing magnetic field creates eddy currents in the thickness of the conductor (steel plate, etc.) . They cause undesirable heating, therefore, various methods are used to eliminate them (in transformers, laminated plates of electrical steel). Note that in some devices eddy currents are used (disk counting counters).

Soon, in 1833, the physicist E. Lenz derived a rule from which the EMF of induction creates a current of such a direction to neutralize the cause of its appearance. For example: a changing magnetic field creates a current in the conductor. It is directed in such a way that its own magnetic field (it is present around conductors with current) counteracts the original cause.

The phenomenon of electromagnetic induction allowed the development of electrical engineering up to its present state. It is difficult to provide a complete list of equipment that uses it. For example, the work of generators in power plants is based on this phenomenon. True, the design of generating capacities has undergone significant changes since Faraday times, however, the general principle remains the same: lines of high magnetic field intensity cross current-conducting windings, resulting in EMF and, in the presence of a closed loop, electric current. In addition to generators and motors, the phenomenon of induction is used, for example, in transformers.