Types of Electric Current

There are two types of electrical current: direct current (DC) and alternating current (AC). Although both kinds of electricity make our lives easier, their use and the production cost are different. They are both caused by the movement of electrons through a conductor; however, the behavior of the conductor electrons is different in each one of the electrical current, as their sources of generation are also different.

DC is the electrical power that we generate through a battery, which is a chemical form of energy stored in an electric cell. It is called ‘direct’ current because the conductor atom electrons continuously flow in only one direction in a closed circuit, always circulating in one way; so, we also say it is a direct electrical current because it is a sustained current. The first DC battery was invented by the Italian physicist Alessandro Volta in 1800 as it was called ‘Voltaic pile‘. We use DC in electronics to power electronic devices, such as flashlights, radio sets, cell phones, tablets, etc. The battery used in a car is called ‘accumulator’. In the 2nd half of the 19th century, Thomas Alba Edison promoted and supported the generation and use of direct current to be used massively by the population and for lighting the streets. However, it was very expensive to produce and specially to distribute over a large area.

AC is generated when a metal conductor is exposed to a magnetic field, whose positive and negative poles  are alternatingly changed, triggering a flow of electrons whose direction also changes. As the magnetic field poles are inverted, so changes the direction of electrons flow, first going one way, next going the other way in a fraction of a second, generating waves. AC is produced by turbine-driven generators in a power plant, like a coal, gas or nuclear power plant.

Most of the AC power plants use steam to propel the turbines, which in turn drive the generators, whose rotors induce alternating current in their stators through electrical magnets they are fitted with. In order to produce steam, power plants need a boiler or a series of boilers, which can be heated either with coal or gas. A nuclear power plant employs uranium rods submerged in water to produce steam, which propels the turbine.

We can say that the father of AC and the AC motor is Nikola Tesla, a Croatian who immigrated to the United States. Although a discharge of AC can kill you, it is a lot cheaper to produce and to distribute over long distance. To keep up AC voltage levels over long distances distribution, we use step-up transformers. DC, on the other hand, is a lot more expensive to generate and to distribute.