Browse Definitions :
Definition

watt per steradian

The watt per steradian (W · sr -1 ) is the standard unit of radiant intensity. Reduced to base units in the International System of Units ( SI ), it is the equivalent of a kilogram meter squared per second cubed per steradian (kg · m 2 · s -3 · sr -1 ).

A point source of electromagnetic (EM) power that radiates equally well in all directions, and whose output is 1 W · sr -1 , has a total output power of 4 p (approximately 12.5664) watt s (W). This is because there are 4 p steradians in three-dimensional space with respect to a point of reference. The watt per steradian can be used to define the radiant intensity at any EM wavelength , from low-frequency radio waves through the gamma-ray spectrum. For visible light, in the wavelength range of approximately 390 to 770 nanometers (nm), the lumen is the preferred unit.

Suppose an electromagnetic field having P watts of total power is radiated from an isotropic emitter (that is, a point source that radiates equally well in all directions). Then the radiant intensity, P' , in watts per steradian is given by the following formula:

P' = P / (4 p )

Also see electromagnetic field , lumen , power , International System of Units ( SI ), steradian , and watt .

This was last updated in September 2005

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • California Consumer Privacy Act (CCPA)

    The California Consumer Privacy Act (CCPA) is legislation in the state of California that supports an individual's right to ...

  • compliance audit

    A compliance audit is a comprehensive review of an organization's adherence to regulatory guidelines.

  • regulatory compliance

    Regulatory compliance is an organization's adherence to laws, regulations, guidelines and specifications relevant to its business...

SearchSecurity

  • endpoint detection and response (EDR)

    Endpoint detection and response (EDR) is a category of tools and technology used for protecting computer hardware devices–called ...

  • ransomware

    Ransomware is a subset of malware in which the data on a victim's computer is locked, typically by encryption, and payment is ...

  • single sign-on (SSO)

    Single sign-on (SSO) is a session and user authentication service that permits an end user to enter one set of login credentials ...

SearchHealthIT

SearchDisasterRecovery

  • 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. 

  • business continuity software

    Business continuity software is an application or suite designed to make business continuity planning/business continuity ...

SearchStorage

  • blockchain storage

    Blockchain storage is a way of saving data in a decentralized network which utilizes the unused hard disk space of users across ...

  • disk mirroring (RAID 1)

    RAID 1 is one of the most common RAID levels and the most reliable. Data is written to two places simultaneously, so if one disk ...

  • RAID controller

    A RAID controller is a hardware device or software program used to manage hard disk drives (HDDs) or solid-state drives (SSDs) in...

Close