/ˌeɪ ˈsiː/
noun … “Electric current that periodically reverses direction.”
AC, short for Alternating Current, is a type of electrical current in which the flow of electric charge reverses direction periodically, typically in a sinusoidal waveform. AC is the standard form of electricity delivered by power grids because it can be easily transformed to different voltages for efficient long-distance transmission.
Unlike DC, which flows in a single direction, AC continuously changes polarity and magnitude, allowing devices such as transformers to step voltage up or down without significant energy loss. AC is widely used to power homes, industrial equipment, and most household appliances.
Key characteristics of AC include:
- Periodic reversal: current alternates direction at a fixed frequency (e.g., 50 or 60 Hz).
- Variable amplitude: voltage and current vary continuously over time.
- Efficient transmission: high-voltage AC reduces energy loss over long distances.
- Conversion capability: AC can be converted to DC using rectifiers.
- Standardization: widely used for power grids worldwide.
Workflow example: AC powering a household device:
ac_wall_voltage = 120 -- volts, typical in North America
device_input = transformer.step_down(ac_wall_voltage, 12)
device.power(device_input)
Here, AC voltage from the wall is stepped down and conditioned to safely power an electronic device.
Conceptually, AC is like water sloshing back and forth in a pipe, constantly changing direction but delivering energy to a turbine or generator efficiently.
See DC, Transformer, Rectifier, Power Supply, Electricity.