vaihtosähkövirran

Vaihtosähkövirta, often abbreviated as AC (alternating current), is an electric current which periodically reverses direction. This is in contrast to direct current (DC), where the flow of electric charge is only in one direction. The voltage of an AC supply also reverses its polarity periodically.

The waveform of AC is typically sinusoidal, meaning the voltage and current change smoothly over time following a sine wave. However, other waveforms such as square or triangular waves are also possible and used in specific applications. The frequency of AC, measured in Hertz (Hz), indicates how many times the current reverses direction per second. In most of the world, the standard frequency for power grids is 50 Hz or 60 Hz.

AC power is generated by alternators, which utilize electromagnetic induction. A rotating magnetic field within a stationary coil of wire, or vice versa, induces an alternating voltage. This alternating voltage then drives an alternating current through a circuit.

The main advantage of AC over DC for power transmission is its ability to be easily transformed to different voltage levels using transformers. This allows for efficient transmission of electricity over long distances at high voltages, reducing power loss, and then stepping down the voltage to safer levels for use in homes and industries. Most household electricity is supplied as AC.