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

### 1 comment

Send me notifications when other members 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

## SearchCompliance

• ### PCAOB (Public Company Accounting Oversight Board)

The Public Company Accounting Oversight Board (PCAOB) is a Congressionally-established nonprofit that assesses audits of public ...

• ### cyborg anthropologist

A cyborg anthropologist is an individual who studies the interaction between humans and technology, observing how technology can ...

• ### RegTech

RegTech, or regulatory technology, is a term used to describe technology that is used to help streamline the process of ...

## SearchSecurity

• ### email spam

Email spam, or junk email, is unsolicited bulk messages sent through email with commercial, fraudulent or malicious intent.

• ### distributed denial of service (DDoS) attack

A distributed denial-of-service attack occurs when an attack originates from multiple computers or devices, usually from multiple...

• ### application whitelisting

Application whitelisting is the practice of identifying applications that have been deemed safe for execution and restricting all...

## SearchHealthIT

• ### athenahealth Inc.

Based in Watertown, Mass., athenahealth Inc. is a leading vendor of cloud-based EHRs for small to medium-sized physician ...

• ### Affordable Care Act (ACA or Obamacare)

The Affordable Care Act (ACA) is legislation passed in 2010 that changed how uninsured Americans enroll in and receive healthcare...

• ### HIPAA Privacy Rule

The Standards for Privacy of Individually Identifiable Health Information, commonly known as the HIPAA Privacy Rule, establishes ...

## SearchDisasterRecovery

• ### disaster recovery as a service (DRaaS)

One approach to a strong disaster recovery plan is DRaaS, where companies offload data replication and restoration ...

• ### data recovery

Data recovery restores data that has been lost, accidentally deleted, corrupted or made inaccessible. Learn how data recovery ...

• ### disaster recovery plan (DRP)

A company's disaster recovery policy is enhanced with a documented DR plan that formulates strategies, and outlines preparation ...

## SearchStorage

• ### yottabyte (YB)

A yottabyte is a measure of theoretical storage capacity and is 2 to the 80th power bytes, or, in decimal, approximately 1,000 ...

• ### Kilo, mega, giga, tera, peta, exa, zetta and all that

Kilo, mega, giga, tera, peta, exa, zetta are among the list of prefixes used to denote the quantity of something, such as a byte ...

• ### brontobyte

A brontobyte is a measure of memory or data storage that is equal to 10 to the 27th power of bytes.

## SearchSolidStateStorage

• ### SSD caching

SSD caching, also known as flash caching, is the temporary storage of data on NAND flash memory chips in a solid-state drive so ...

• ### NVDIMM (Non-Volatile Dual In-line Memory Module)

An NVDIMM (non-volatile dual in-line memory module) is hybrid computer memory that retains data during a service outage.

• ### NAND mirroring

NAND mirroring has been proposed to break the security in certain portable devices that use NAND flash memory for encryption.

## SearchCloudStorage

• ### RESTful API

A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

• ### cloud storage infrastructure

Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

• ### Zadara VPSA and ZIOS

Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close