vekselspændingen

Vekselspænding, often abbreviated as AC (Alternating Current), is an electric current which periodically reverses direction, unlike direct current (DC) which flows only in one direction. This reversal of direction is accompanied by a reversal of voltage. The most common waveform for vekselspænding is a sinusoidal wave, where the voltage and current vary smoothly over time between positive and negative maximum values. The rate at which this change occurs is called the frequency, measured in Hertz (Hz), indicating cycles per second. In many parts of the world, the standard mains electricity supply operates at 50 Hz or 60 Hz.

The primary advantage of vekselspænding is its ability to be easily transformed to higher or lower voltages using transformers. This is crucial for efficient 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. The generation of vekselspænding typically occurs in alternators, which use electromagnetic induction to convert mechanical energy into electrical energy. While DC is used in many electronic devices and batteries, AC is the dominant form of electricity delivered through power grids worldwide due to its transmission efficiency and the ease with which its voltage can be manipulated.