There are two basic types of current – AC and DC. A conventional electric battery, for example, provides a constant current with a voltage of 1.5 volt, and the installation and operation of an alternating electric current with a voltage of 220 V. Transformers are used solely to convert the alternating electric current. Constant current transformation can not be.

## How is the transformation of the current

The simplest transformer consists of a metal core, for example of the W-shaped plates, and the two windings primary and secondary. Winding electrically are not connected, the electric power transmission is carried out by electromagnetic induction.

Why do we need transformer? It allows to the extent necessary to change the voltage and the amperage. For example, you have a light bulb at 2.5 V. It is not directly connected to the mains of 220 V, it will instantly burn out. To work properly, you need to lower the voltage from 220 V to 2.5 V; that is, to reduce it almost 100 times.

This task allows to solve the transformer. Its primary winding has a sufficiently large number of turns, for example, 1000. Because of this it can easily withstand a voltage of 220 V, the inclusion of windings in the network does not cause a short circuit. The primary winding is wound over the secondary, but the number of turns is much less. If in our example, 1000 coils for 220 V, 1 revolution then you have to 0.22 V. We need 2.5 V. it is Easy to calculate that for normal operation of light bulbs with a voltage of 2.5 V is necessary to wind the secondary winding of 11-12 turns.

## The field of transformers, electric current

To transfer electricity over long distances, use a high-voltage power lines. It is transmitted by alternating current, since the transfer of the permanent loss of electricity is too high. Losses decrease with increasing voltage, so on the main directions we use voltage in the hundreds of thousands of volts.

To obtain a high voltage for transmission over a distance, then re-convert it to the right consumers, and transformers are used. As a rule, it is a powerful oil-cooled transformers, designed for high voltage.

Small transformers used in electronic equipment and household appliances, they help to lower the voltage of 220 V to a lower required to power electronic components. Sometimes transformers are used for galvanic isolation – in this case, the number of turns in the primary and secondary winding of the same. From the secondary winding off the same voltage, which acts on the primary winding, but this is another chain that does not have direct electrical connection with the primary winding.

Today, in many cases it is not possible to replace the transformers of alternating current some other devices. So there is no doubt that they will be used for a very long time.