vaihtovirrällä

Vaihtovirralla, often abbreviated as AC (Alternating Current), is an electric current that periodically reverses direction and changes its magnitude continuously with time. This is in contrast to direct current (DC), which flows in only one direction. The most common waveform for AC is a sinusoidal wave, where the voltage and current vary smoothly between a positive and negative peak value.

The generation of AC is typically achieved through electromagnetic induction. A rotating magnetic field or a rotating coil within a stationary magnetic field, as found in alternators, induces a voltage that changes polarity as the coil or field rotates. This principle is fundamental to how electricity is generated in power plants and transmitted over long distances.

The primary advantage of AC over DC for power transmission is the ease with which its voltage can be changed using transformers. Transformers allow AC voltage to be stepped up to very high levels for efficient transmission with minimal energy loss over long distances, and then stepped down to safer, usable levels for homes and businesses. This voltage transformation capability is not easily achievable with DC.

AC is the standard form of electrical power delivered to homes and businesses worldwide. Common household frequencies are 50 Hz or 60 Hz, depending on the region. This means the current reverses direction 50 or 60 times every second. Many common electrical devices, such as motors, lights, and heating elements, are designed to operate directly on AC power.