4. Types of current.

Some electrical devices use batteries and some must be connected to the electric mains. Both provide electricity, but in different ways.

4.1. Direct current.
Between the terminals of battery, there is a continuous, stable flow of energy, if we use a voltemeter 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.