Browse Definitions :
Definition

lux (lx)

The lux (symbolized lx) is the unit of illuminance in the International System of Units ( SI ). It is defined in terms of lumen s per meter squared (lm/m 2 ). Reduced to SI base units, one lux is equal to 0.00146 kilogram per second cubed (1.46 x 10 -3 kg / s 3 ).

One lux is the equivalent of 1.46 milliwatt (1.46 x 10 -3 W) of radiant electromagnetic (EM) power at a frequency of 540 terahertz (540 THz or 5.40 x 10 14 Hz ), impinging at a right angle on a surface whose area is one square meter. A frequency of 540 THz corresponds to a wavelength of about 555 nanometer s (nm), which is in the middle of the visible-light spectrum.

The lux is a small unit. An alternative unit is the watt per meter squared (W / m 2 ). To obtain lux when the illuminance in watts per meter squared is known, multiply by 683. To obtain watts per meter squared when the illuminance in lux is known, divide by 683 or multiply by 0.00146.

Illuminance varies inversely with the square of the distance from the source on a free-space line of sight. If the distance is doubled, the illuminance is cut to 1/4; if the distance increases by a factor of 10, the illuminance becomes 1/100 (0.01 times) as great.

Also see candela , electromagnetic field , lumen , steradian , watt per meter squared , and International System of Units ( SI ).

This was last updated in March 2011

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.

SearchCompliance

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

  • PCI DSS (Payment Card Industry Data Security Standard)

    The Payment Card Industry Data Security Standard (PCI DSS) is a widely accepted set of policies and procedures intended to ...

  • risk management

    Risk management is the process of identifying, assessing and controlling threats to an organization's capital and earnings.

SearchSecurity

  • tokenization

    Tokenization is the process of replacing sensitive data with unique identification symbols that retain all the essential ...

  • incident response

    Incident response is an organized approach to addressing and managing the aftermath of a security breach or cyberattack, also ...

  • Federal Information Security Management Act (FISMA)

    The Federal Information Security Management Act (FISMA) is United States legislation that defines a framework of guidelines and ...

SearchHealthIT

SearchDisasterRecovery

  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

  • cloud disaster recovery (cloud DR)

    Cloud disaster recovery (cloud DR) is a combination of strategies and services intended to back up data, applications and other ...

SearchStorage

Close