4. TYPES OF CURRENT

4.1 Direct current

Between the terminals of a battery, there is a continous, stable flow of energy. This is called direct current.

4.2 Alternating current

If we measured the voltage of an electrical socket, the results could be represented in a graph like the one below:

The variation of any electrical parameter over a period of time (in this case the electric current) is an electric signal.

The tension or voltage of domestic electricity is an alternating signal because it alternates between positive and negative values. Its waveform is also sinusoidal, with a smooth, regular shape.

4.3 The efficiency of alternating current 

The average power of alternating current is equal to the direct current that is needed to produce the same effect. In the case of an alternating sinusoidal, current, the average power would be as foollows

                                                                       V ef=V max/(Square root) 2

4.4 Transformers

Is a difference between alternating and direct current. Alternating current can be increased or decreased by a transformer.

Transformer consist of two windings made of copper wire. If we apply an .alternating current to one of them, it will produce a certain voltage in the other.