lumen, lm (unit)

This page documents an OPTIMADE Unit Definition. See https://schemas.optimade.org/ for more information.

ID: https://schemas.optimade.org/defs/v1.2/units/si/general/lumen
Definition name: lumen

Unit name: lumen
Latin symbol: lm
Display symbol: lm

Description: A derived SI unit for luminous flux equal to cd┬Ěsr using the current, or one of the historical, definitions of the SI units.

"The lumen is the luminous flux emitted in a steradian by a uniform point source with a luminous intensity of one candela." [9th CGPM meeting in 1946]

The lumen was defined at the 9th CGPM meeting in 1946, implicitly redefined via the redefinitions of the second at the 13th CGPM Meeting in 1967, resolution 1, the candela at the 16th CGPM Meeting in 1979, resolution 3, the metre at the 17th CGPM Meeting in 1983, resolution 1, and the candela (implicitly redefined via the kilogram) at the 26th CGPM Meeting (2018), resolution 1.

This is a generalized definition taken to reference the current, or one of the historical, SI unit definitions. This definition is intended for situations when it is not possible to be more precise, e.g., in contexts where data have been collected that uses different historical SI definitions.

Resources:

Compatibility: (other definitions that are covered by the above definition)

Formats: [JSON] [MD]

JSON definition:

{
    "$id": "https://schemas.optimade.org/defs/v1.2/units/si/general/lumen",
    "$schema": "https://schemas.optimade.org/meta/v1.2/optimade/physical_unit_definition.json",
    "title": "lumen",
    "symbol": "lm",
    "display-symbol": "lm",
    "description": "A derived SI unit for luminous flux equal to cd\u00b7sr using the current, or one of the historical, definitions of the SI units.\n\n\"The lumen is the luminous flux emitted in a steradian by a uniform point source with a luminous intensity of one candela.\" [9th CGPM meeting in 1946]\n\nThe lumen was defined at the 9th CGPM meeting in 1946, implicitly redefined via the redefinitions of the second at the 13th CGPM Meeting in 1967, resolution 1, the candela at the 16th CGPM Meeting in 1979, resolution 3, the metre at the 17th CGPM Meeting in 1983, resolution 1, and the candela (implicitly redefined via the kilogram) at the 26th CGPM Meeting (2018), resolution 1.\n\nThis is a generalized definition taken to reference the current, or one of the historical, SI unit definitions.\nThis definition is intended for situations when it is not possible to be more precise, e.g., in contexts where data have been collected that uses different historical SI definitions.",
    "compatibility": [
        "https://schemas.optimade.org/defs/v1.2/units/si/1960/named/lumen",
        "https://schemas.optimade.org/defs/v1.2/units/si/1967/named/lumen",
        "https://schemas.optimade.org/defs/v1.2/units/si/1979/named/lumen",
        "https://schemas.optimade.org/defs/v1.2/units/si/1983/named/lumen",
        "https://schemas.optimade.org/defs/v1.2/units/si/2019/named/lumen"
    ],
    "resources": [
        {
            "relation": "Definition and establishment of the SI unit system at the 11th CGPM meeting (1960), resolution 12.",
            "resource-id": "https://www.bipm.org/en/committees/cg/cgpm/11-1960/resolution-12"
        },
        {
            "relation": "Redefinition of the candela at the 16th CGPM Meeting in 1979, resolution 3.",
            "resource-id": "https://www.bipm.org/en/committees/cg/cgpm/16-1979/resolution-3"
        },
        {
            "relation": "Redefinition of the second in the 13th CGPM Meeting in 1967, resolution 1",
            "resource-id": "https://www.bipm.org/en/committees/cg/cgpm/13-1967/resolution-1"
        },
        {
            "relation": "Redefinition of the metre at the 17th CGPM meeting in 1983, resolution 1",
            "resource-id": "https://www.bipm.org/en/committees/cg/cgpm/17-1983/resolution-1"
        },
        {
            "relation": "Redefinition of the kilogram at the 26th CGPM Meeting (2018), resolution 1",
            "resource-id": "https://www.bipm.org/en/committees/cg/cgpm/26-2018/resolution-1"
        },
        {
            "relation": "Wikipedia article describing the unit",
            "resource-id": "https://en.wikipedia.org/wiki/Lumen_(unit)"
        }
    ],
    "defining-relation": {
        "base-units": [
            {
                "symbol": "cd",
                "id": "https://schemas.optimade.org/defs/v1.2/units/si/general/candela"
            },
            {
                "symbol": "sr",
                "id": "https://schemas.optimade.org/defs/v1.2/units/si/general/steradian"
            }
        ],
        "base-units-expression": "cd*sr"
    },
    "x-optimade-definition": {
        "label": "lumen_si_general",
        "kind": "unit",
        "format": "1.2",
        "version": "1.2.0",
        "name": "lumen"
    }
}