IEVref:112-02-10ID:
Language:enStatus: Proposed
Term: candela
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Symbol: cd
Definition: SI unit of luminous intensity, taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, to be 683 when expressed in the unit lm W−1

Note 1 to entry: The definition in the SI Brochure is: "The candela, symbol cd, is the SI unit of luminous intensity. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, to be 683 when expressed in the unit lm W−1, which is equal to cd sr W−1, or cd sr kg−1m−2 s3, where the kilogram, metre and second are defined in terms of h, c and ΔνCs."

Note 2 to entry: This definition applies to photopic vision, mesopic vision and scotopic vision.

Note 3 to entry: The candela is one of the seven SI base units: second (s), metre (m), kilogram (kg), ampere (A), kelvin (K), mole (mol) and candela (cd).


Publication date:
SourceSI Brochure, 9th edition, 2019, 2.3.1, modified – The definition in the SI Brochure has been revised to comply with the IEV rules. Notes 1 to 3 to entry have been added.
Replaces:112-02-10:2020-12
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