Vaihtosähköllä

Vaihtosähköllä, often translated as "with alternating current" or "AC-powered," refers to the operation of electrical devices or systems using alternating current as their power source. Alternating current is an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction. The most common waveform for AC is a sinusoidal wave, where the voltage and current vary smoothly between positive and negative values.

The primary advantage of alternating current is its ability to be easily transformed to different voltage levels using transformers. This is crucial for efficient long-distance power transmission, as high voltages reduce energy loss over wires. Power plants generate electricity at a relatively low voltage, which is then stepped up to very high voltages for transmission. Before reaching homes and businesses, this high voltage is stepped down in stages to safer, usable levels.

Many household appliances and electronic devices are designed to run on AC power directly from the electrical grid. However, some devices, particularly those with sensitive electronics or motors requiring precise speed control, may use AC power but contain internal components like rectifiers and power supplies to convert it to DC for their internal operations. Devices that are explicitly DC-powered, such as batteries, require a power adapter to convert AC from the wall outlet to the appropriate DC voltage. The ubiquitous nature of AC power has made it the standard for electrical grids worldwide.