phenomenon of electromagnetic induction in electrical engineering is one of the basic.It has been empirically discovered back in 1831 by the English physicist Michael Faraday.While it was known that between a conductor and a magnet located near the interaction.It was believed that the fixed charges interact via electric field, and their movement (current) seen through a magnetic field.However, the prospect of the practical use of this knowledge to the results of the experiment Faraday was rather vague.In fact, the scientist who discovered the phenomenon of electromagnetic induction, initiated the basis of modern electronics.
experience itself was pretty simple: a permanent magnet bar began to move, and was nominated in the central space between the turns of the coil.Conclusions coils were connected to the sensing device for measuring small currents and voltages.
It has been observed that when the magnet galvanometer needle deviates from the zero point.Moreover, the deviation was greater, more intense moving magnet.If we remember that it has two poles and lines the field strength, it becomes obvious relationship between the magnetic flux and the induced current is created.
spontaneously Since current in the circuit can not occur, the logical conclusion was made about the appearance of an electromotive force (EMF), which in turn allows current to appear.Faraday's law of induction suggests that the impact on the wire of time-varying magnetic field causes the appearance of a changing electric field and, if you have a closed circuit current.
phenomenon of electromagnetic induction allowed him to make a revolutionary conclusion: the cause of the electric field can be not only charge but also a changing magnetic field.Later it was formulated generalization.Thus, Faraday's law of electromagnetic induction states that: creates a magnetic field EMF is directly dependent on the rate of change of magnetic flux.The strength of the generated current to the closed loop is calculated by Ohm's law.
phenomenon of electromagnetic induction is characteristic not only for conductor but also for massive conductive bodies.Thus, the changing magnetic field creates thicker wire (steel plate, etc.). Eddy current.They cause unwanted heating, so use a variety of methods to address them (in transformers laminated electrical steel plate).Note that in some devices, eddy currents are used (disk counters counting).
Soon, in 1833, the physicist E. Lenz brought a rule, on the basis of which, induced emf produces a current of such direction to neutralize the cause of its occurrence.For example, the changing magnetic field induces a current in the conductor.It is directed in such a way that its own magnetic field (it is present around the current-carrying conductors) counteracted the root cause.
phenomenon of electromagnetic induction allowed to develop to its current electrical condition.It is difficult to present a full list of equipment it uses.For example, job generators in power plants based on this phenomenon.However, the construction of generating capacity has undergone significant changes since the time of Faraday, however, the general principle remains the same: the lines of the magnetic field with a high frequency cross the conductive coil, resulting in an electromotive force and, if closed-loop current.Furthermore generators and motors, induction phenomenon is used, for example, in transformers.