Definition

Noun: A luminous flux unit is a unit of measurement for the total quantity of visible light emitted by a source per unit of time. It measures luminous flux, which is the perceived power of light, adjusted for the sensitivity of the human eye.

Usage

This term is used in scientific, technical, and engineering contexts, particularly in physics, lighting design, and photometry. It specifies the standard units for quantifying the flow of visible light. - The lumen is the SI unit for luminous flux. - Engineers calculated the required luminous flux for the room in lumens.

Examples

Advanced Usage

• Photometric Quantities: A luminous flux unit is foundational in photometry, relating to other measures like illuminance (luminous flux per unit area, measured in lux) and luminous intensity.
• System International (SI): The coherent SI unit for luminous flux is the lumen (lm), which is a core part of the International System of Units.

Variants and Related Words

• Lumen (lm): The SI derived unit of luminous flux. One lumen is defined as the luminous flux emitted into a unit solid angle by an isotropic point source with a luminous intensity of one candela.
• Luminous Flux: The underlying physical quantity that these units measure.
• Illuminance: The luminous flux incident on a surface per unit area, for which the unit is the lux (lx = lm/m²).

Synonyms

• Unit of luminous flux
• Photometric unit (in the specific context of light measurement)

Notes

• The term "luminous flux unit" is a categorical term for any unit in this class (e.g., lumen). It is not a specific unit name itself.
• It is distinct from units of radiant flux (which measures total electromagnetic power, in watts) because it is weighted by the spectral sensitivity of the human eye.

Noun

1. a measure of luminous flux per unit area