AC vs. DC — What's the Difference?

AC, or alternating current, is characterized by the flow of electric charge that periodically reverses direction. This feature allows for efficient transmission of electricity over long distances with minimal energy loss. On the other hand, DC, or direct current, maintains a constant flow of electric charge in one direction, making it stable and predictable for devices that require a consistent voltage level.

While AC is the standard used in most home and industrial power supplies due to its ability to be easily transformed between high and low voltages, DC is preferred in applications like electronic devices, electric vehicles, and solar power systems, where batteries store power as DC. This is because DC’s consistent voltage is ideal for sensitive electronics that require stable power.

Transformers, which are critical for adjusting voltage levels, work only with AC. This capability is essential for efficient power distribution, as high voltages can be used for transmission to reduce losses, then lowered for safe home and business use. Conversely, DC cannot be easily transformed, which was a major limitation before the development of modern electronic technology that allows for efficient DC to AC conversion.

AC power systems can deliver power across vast networks, such as national grids, with stations that handle the conversion and regulation of voltages. DC systems, while improving with technology, are generally used in more localized settings, like inside electronic devices or for linking power grids through high-voltage DC (HVDC) transmission.

Electrical safety with AC and DC also differs; AC's alternating nature can be more dangerous in certain situations due to it potentially causing more severe muscular contractions. However, DC tends to be less risky at lower voltages but can be more dangerous at high voltages because it causes a continuous current which can lead to thermal burns.