Alternating Current (AC)

Definition

Alternating Current (AC): An electrical current in which the voltage difference reverses direction periodically at a fixed frequency.

Purpose

The primary purpose of alternating current (AC) is to enable the efficient transmission and distribution of electricity over long distances. AC's ability to change voltage levels using transformers makes it suitable for powering homes, businesses, and industries. This versatility and efficiency have made AC the standard for electrical power systems worldwide.

Examples of Use

1. Household Electricity: The electricity supplied to homes is typically AC, allowing for the operation of various appliances such as refrigerators, televisions, and lighting.
2. Industrial Machinery: Factories and industrial plants use AC to power heavy machinery and equipment, benefiting from the ease of voltage transformation and efficient energy distribution.
3. Transportation: AC is used in electric trains and some electric vehicles, providing reliable power for transportation systems.
4. Power Grids: AC is the backbone of national and international power grids, facilitating the transmission of electricity from power plants to end users over vast distances.
5. Consumer Electronics: Many electronic devices, such as computers and smartphones, use AC adapters to convert the alternating current from wall outlets into the direct current (DC) required by the devices.

Related Terms

• Direct Current (DC): An electrical current that flows in one direction only, used in batteries and some electronic devices.
• Transformer: A device that changes the voltage of an AC power supply, enabling efficient power transmission and distribution.
• Frequency: The number of times the AC voltage reverses direction per second, measured in Hertz (Hz). Common frequencies are 50 Hz and 60 Hz, depending on the region.
• Phase: The distribution of alternating current in cycles, with single-phase and three-phase being common configurations in power systems.
• Voltage: The electric potential difference that drives the current, alternating in AC systems to facilitate power distribution.

Notes

• The standard frequency of AC power varies by region, typically 60 Hz in North America and 50 Hz in Europe and many other parts of the world.
• AC can be converted to DC using rectifiers, which is necessary for devices that require a steady, unidirectional current.
• Nikola Tesla and George Westinghouse were pivotal in the development and promotion of AC power systems in the late 19th century, leading to widespread adoption.