vaihtovirroille

Vaihtovirta, often abbreviated as AC (alternating current), is an electric current that periodically reverses direction, in contrast to direct current (DC), which flows only in one direction. The voltage of a typical AC circuit also reverses its polarity along with the current. This reversal happens at a specific frequency, measured in Hertz (Hz), which indicates the number of cycles per second. Common frequencies for AC power grids are 50 Hz and 60 Hz.

The primary advantage of AC over DC for power transmission is its ability to be easily transformed to different voltage levels. Transformers, devices that utilize electromagnetic induction, can efficiently step AC voltage up or down. This is crucial for long-distance power transmission, where high voltages are used to minimize energy loss, and then stepped down to safer, usable levels for homes and businesses.

AC was famously championed by Nikola Tesla and George Westinghouse in the late 19th century, overcoming the advocacy for DC by Thomas Edison. The development of AC power systems led to the widespread electrification we see today. Applications of AC are vast, including powering most household appliances, lighting, and industrial machinery. While DC is dominant in electronics and battery-powered devices, AC remains the standard for bulk electrical power generation and distribution.