vekselstrømmer

Vekselstrømmer, often abbreviated as AC from the English term alternating current, refers to an electric current which periodically reverses direction. This is in contrast to direct current (DC), where the flow of charge is only in one direction. The most common waveform for AC is a sinusoidal wave, but other shapes like triangular or square waves are also possible.

The key characteristic of AC is its periodically varying voltage and current. This variation is typically described by its frequency, measured in Hertz (Hz), which indicates the number of cycles the current completes per second. For example, household electricity in many parts of the world operates at 50 Hz or 60 Hz. The voltage and current also have a peak value and an RMS (root mean square) value, which is a measure of the effective voltage or current.

Vekselstrømmer are fundamental to modern power distribution systems. They can be easily stepped up or down in voltage using transformers. This ability is crucial for efficiently transmitting electricity over long distances. High voltages reduce current, thereby minimizing resistive losses in the transmission lines. Before reaching homes and businesses, the voltage is then stepped down to safer and usable levels.

The generation of AC typically occurs in generators, where rotating magnetic fields induce a sinusoidal voltage in stationary coils. Hydroelectric, thermal, and nuclear power plants all commonly utilize AC generators. While DC is used in many electronic devices, the vast majority of electrical power generated and distributed globally is in the form of AC.