There are two main types of current - constant and variable.The usual electric battery, for example, provides a direct current voltage of 1.5 volts, and the power supply an alternating electric current with a voltage of 220 V. Transformers are used exclusively for converting alternating electric current.DC transformation can not be.

## How is the transformation of the current

In its simplest form consists of a metal transformer core - for example, a W-shaped plates, and two windings, primary and secondary.The windings are electrically connected to each other is not, the transfer of electrical energy is carried out by electromagnetic induction.

Why do I need a transformer?It allows to the extent necessary to change the voltag
e and current.For example, you have a light bulb to 2.5 V. It can not be connected directly to the mains 220, she immediately burned.That it worked properly, you must reduce the voltage from 220 V to 2.5 V - that is, to reduce its almost 100 times.

this problem and solves the transformer.Its primary winding has a sufficiently large number of turns - for example, 1000. Due to this, it can easily withstand voltage of 220 V, including winding the network does not cause a short circuit.Above the secondary primary winding is wound, but the number of turns it is much less.If in our example 1000 turns are calculated on 220, then 1 round then have to 0.22 V. We need 2.5 V. It is easy to calculate that for the normal operation voltage of 2.5 V light bulbs need to be wound secondary winding of 11-12turns.

## Applications transformers electric current

to transmit electricity over long distances using high voltage power lines.Dispatched just alternating current, since the permanent transfer of power losses are too great.The losses are reduced with the increase in voltage, so the voltage of the main directions is used in hundreds of thousands of volts.

To obtain a high voltage for transmission over a distance, and then re-convert it to the desired consumers and transformers are used.Typically, this powerful oil transformers designed for high voltage.

Small transformers are used in electronic equipment and household appliances, they can reduce the voltage of 220 V to a lower, needed to supply the 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.On the secondary winding is removed at the same voltage, which acts on the primary side, but that is another chain that has no direct electrical connection to the primary winding.

Today, in many cases it is not possible to replace the AC transformer with some other devices.Therefore, there is no doubt that they will be used for a very long time.