Browse Definitions :
Definition

watt

The watt (abbreviated W) is the International System of Units' (SI) standard unit of power (energy per unit time), the equivalent of one jouleper second. The watt is used to specify the rate at which electrical energy isdissipated, or the rate at which electromagnetic energy is radiated, absorbed, or dissipated.

In DC (direct-current) and low-frequency AC (alternating current) electrical circuits andsystems, power is the product of the current and the voltage. Power is alsoproportional to the ratio of the square of the voltage to the resistance, and to the product of the resistanceand the square of the current. Consider a circuit in which the current, voltage, andresistance are all constant. If the current in amperes is represented by I,the voltage (or potential difference) in volts is represented by E, and theresistance in ohms is represented by R, then the following equations hold forpower in watts, represented by P:

P = EI

P = E2/R

P = I2R

In radio-frequency (RF) circuits and systems, the calculation of powerbecomes more complex. This is because, at high frequencies, AC is affected not onlyby resistance, but by reactance. Inthese situations, no simple formulas exist for the calculation of power. However,dissipated or radiated RF power in can be determined by direct measurement using aninstrument called an RF wattmeter.

In situations involving very high or very low power, prefix multipliersare commonly used to obtain power units. As the rate of dissipated or radiated powerincreases, one kilowatt (kW) is equal to 1000 W; one megawatt (MW) is equal to 106W; one gigawatt (GW) is equal to 109 W. As power decreases, one milliwatt(mW) is equal to 0.001 W; one microwatt (µW) is equal to 10-6 W; one nanowatt(nW) is equal to 10-9 W.

This was last updated in April 2005

Join the conversation

1 comment

Send me notifications when other members comment.

Please create a username to comment.

Best..
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

SearchCompliance

SearchSecurity

  • computer worm

    A computer worm is a type of malicious software program whose primary function is to infect other computers while remaining ...

  • Single Sign-On (SSO)

    Single sign-on (SSO) is a session and user authentication service that permits a user to use one set of login credentials (e.g., ...

  • Certified Information Systems Auditor (CISA)

    Certified Information Systems Auditor (CISA) is a certification issued by ISACA to people in charge of ensuring that an ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • disaster recovery team

    A disaster recovery team is a group of individuals focused on planning, implementing, maintaining, auditing and testing an ...

  • cloud insurance

    Cloud insurance is any type of financial or data protection obtained by a cloud service provider. 

SearchStorage

Close