Browse Definitions:
Definition

alternating current (AC)

Also see current, voltage, and direct current.

In electricity, alternating current (AC) occurs when charge carriers in a conductor or semiconductor periodically reverse their direction of movement. Household utility current in most countries is AC with a frequency of 60 hertz (60 complete cycles per second), although in some countries it is 50 Hz. The radio-frequency (RF) current in antennas and transmission lines is another example of AC.

An AC waveform can be sinusoidal, square, or sawtooth-shaped. Some AC waveforms are irregular or complicated. An example of sine-wave AC is common household utility current (in the ideal case). Square or sawtooth waves are produced by certain types of electronic oscillators, and by a low-end uninterruptible power supply (UPS) when it is operating from its battery. Irregular AC waves are produced by audio amplifiers that deal with analog voice signals and/or music.

The voltage of an AC power source can be easily changed by means of a power transformer. This allows the voltage to be stepped up (increased) for transmission and distribution. High-voltage transmission is more efficient than low-voltage transmission over long distances, because the loss caused by conductor resistance decreases as the voltage increases.

The voltage of an AC power source changes from instant to instant in time. The effective voltage of an AC utility power source is usually considered to be the DC voltage that would produce the same power dissipation as heat assuming a pure resistance. The effective voltage for a sine wave is not the same as the peak voltage . To obtain effective voltage from peak voltage, multiply by 0.707. To obtain peak voltage from effective voltage, multiply by 1.414. For example, if an AC power source has an effective voltage of 117 V, typical of a household in the United States, the peak voltage is 165 V.

Nikola Tesla, a Serbian-American scientist, electrical engineer, and inventor, developed the alternating-current (AC) electrical system, as well as radio, the Tesla coil transformer, wireless transmission, and fluorescent lighting.

This was last updated in January 2011

Join the conversation

3 comments

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

Really nice article!!!! Just what I was searching. I will love to share a link here>>>> http://www.crestchic.com>>>>>>> They supply a range of Power Testing and Commissioning equipment for rental use.

Cancel
Question - Do the electrons remain in the Same Place. I contend that first they move forward, then when they move back, they do not return as far.
So the electrons eventually leave the device.
Cancel
Mains electricity is usually generated with an alternator, voltage is generated in a wire when is moved through a magnetic field, either the magnet or the wire coil can be moving part, The coil passes through the north then the south of the magnetic field which is why the current alternates once each revolution. The voltage is at a maximum at the strongest part of the field at one pole then drops to zero then reverses flow in the opposite direction at the other pole. 
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • smart contract

    A smart contract, also known as a cryptocontract, is a computer program that directly controls the transfer of digital currencies...

  • risk map (risk heat map)

    A risk map, also known as a risk heat map, is a data visualization tool for communicating specific risks an organization faces. A...

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

SearchSecurity

  • evil maid attack

    An evil maid attack is a security exploit that targets a computing device that has been shut down and left unattended.  An evil ...

  • Common Body of Knowledge (CBK)

    In security, Common Body of Knowledge (CBK) is a comprehensive framework of all the relevant subjects a security professional ...

  • rootkit

    A rootkit is a program or, more often, a collection of software tools that gives a threat actor remote access to and control over...

SearchHealthIT

  • value-based healthcare

    Value-based healthcare, also known as value-based care, is a payment model that rewards healthcare providers for providing ...

  • health informatics

    Health informatics is the practice of acquiring, studying and managing health data and applying medical concepts in conjunction ...

  • clinical trial

    A clinical trial, also known as a clinical research study, is a protocol to evaluate the effects and efficacy of experimental ...

SearchDisasterRecovery

  • crisis communication

    Crisis communication is a method of corresponding with people and organizations during a disruptive event to provide them with ...

  • Zerto

    Zerto is a storage software vendor that specializes in enterprise-class business continuity and disaster recovery in virtual and ...

  • crisis management plan (CMP)

    A crisis management plan (CMP) is a document that outlines the processes an organization will use to respond to a critical ...

SearchStorage

  • cache memory

    Cache memory, also called CPU memory, is high-speed static random access memory (SRAM) that a computer microprocessor can access ...

  • RAID 10 (RAID 1+0)

    RAID 10, also known as RAID 1+0, is a RAID configuration that combines disk mirroring and disk striping to protect data.

  • Red Hat OpenStack Platform

    Red Hat OpenStack Platform is a commercially supported distribution of open source OpenStack software designed to build and ...

SearchSolidStateStorage

  • hybrid hard disk drive (HDD)

    A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.

Close