What is the Difference Between Alternating Current (AC) and Direct Current (DC)?

Electricity is essentially a flow of electric charge in a circuit and is required to enable functioning of the various devices that form the center of our modern world. While it may all look the same to us, electric current is primarily classified into two types based on its ability to deliver power: direct current and alternating current. The way the charge moves through the conductor determines whether the current is direct or alternating. Both kinds of electricity are widely used in electrical and electronic circuits; however, their characteristics dictate their use for specific purposes.

As the name implies, direct current (DC) is unidirectional; as such, the flow of electric charge is consistently in the same direction. In alternating current (AC) on the other hand, the flow of the electric charge exhibits a cyclical change in direction. The direction of the current reverses or alternates a certain number of times per second; for example, in the U.S., it is 60 times per second while in Europe, 50. It is this periodic back-and-forth motion that gives alternating current its name.

If one were to visualize this fundamental difference between the two graphically, DC would be linear while AC would generate a waveform where the up curve corresponds to the current moving in a positive direction and the down curve, the alternate cycle where the current flows in the opposite direction.

Circuits that involve batteries illustrate direct current as the charge always flows in the same direction between the two terminals. As such, DC is the preferred type of power for most of the electronic devices we use. The characteristic of alternating current to move in waves makes it an efficient traveler over long distances. AC is therefore the standard electricity format used by most power distribution systems to deliver electricity for commercial and residential use and the power at the outlets we plug our devices into.

Alternating current and direct current coexist in our daily life. A qualified electrician can help maintain that by inspecting the electrical systems in your home or business. Call an electrician to keep your electrical systems in optimal health, or sign up with your local IEC chapter if you would like to learn how to work with AC systems.

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