TYPES OF CURRENT

Some electrical devices use batteries and some must ve connected to the electric mains

DIRECT CURRENT

Between the terminals of abattery, there is a continuous, stable flow of energy. of we use a voltmeter to measure the current in a car battery, the result will always be 12 volts. This is called direct current.
In the same way, if we connect a light bulb to a battery, the electrons always flow in the same direction with the same current.

ALTERNATING CURRENT

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

-The current egins at 0 V and increases to 325V

-The current decreases from 325V to 0V

-The current becomes negative and decreases to -325V

-The current increases to 0V

The variation of any electrical parameter over a period of time is an electric signal. 

The tension of voltage of domestic elctricity is an alternating signal beacause it altenates between positive and negative values. Its waveforms is also sinusoidal, with a smiith, regular shape.

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 te case of an alternating sinusoidal current, the average power would be as follows

                                                   Vef= Vmax/√2

TRANSFORMERS

Alternating current can be increased or decreased by a transformer. They consist of two windings made of copper wire. If we apply an alternating current to one of them (V1) it'll produce a certain voltage in the other (V2). The value will depend on the number of times that the copper wire has been wrapped around each winding, represented as n1 and n2:

                                                     V1/V2=n1/n2