Alternating Current

Alternating current (AC) is an electric current that flows back and forth in a circuit at regular intervals.

1. Periodic Reversal: AC periodically changes direction, flowing first in one direction (positive half-cycle) and then in the opposite direction (negative half-cycle), repeating this cycle continuously.
2. Common Usage: AC is the type of current used in most residential and commercial buildings to power appliances and lighting. It is also the type of current produced by alternators in vehicles.
3. Contrast with Direct Current (DC): Unlike direct current, which flows steadily in one direction, AC reverses direction. This periodic reversal is a defining feature of AC.
4. Waveform: AC current typically follows a sinusoidal waveform, where the current and voltage vary smoothly and continuously over time. The shape of the waveform depends on the frequency of the AC, which is typically 50 Hz or 60 Hz in most power systems.
5. Transmission and Distribution: AC is preferred for long-distance transmission of electric power because it can be easily converted to different voltage levels using transformers, which are more efficient with AC than DC.
6. Rectification: In applications where DC is required (such as in many electronic devices), AC must be converted to DC using devices called rectifiers. This process involves changing the alternating nature of the current to a steady, unidirectional flow.

Alternating current is fundamental to modern electrical systems, providing a practical means to generate, transmit, and utilize electric power efficiently across a wide range of applications.