valgustugevuse mõõtühik; SI süsteemi põhiühik

antudsuunalise valgustugevuse ühik, mille määratlemisel on aluseks võetud 540 × 1012 hertsise sagedusega monokromaatilise kiirguse valgusviljakuse fikseeritud arvväärtus Kcd, milleks on 683 väljendatuna ühikus lm·W-1, mis on cd·sr·W-1 või cd·sr·kg-1·m-2·s3, kus kilogramm, meeter ja sekund on määratletud vastavalt h, c ja ΔvCs alusel, SI unit of luminous intensity, equal to the luminous intensity in a given direction, of a source that emits monochromatic radiation of frequency 540 × 1012 Hz and has a radiant intensity in that direction of 1/683 W/sr, SI unit of luminous intensity in a given direction. 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−1 m−2 s3, where the kilogram, metre and second are defined in terms of h, c and ∆νCs.

antudsuunalise valgustugevuse ühik, mille määratlemisel on aluseks võetud 540 × 1012 hertsise sagedusega monokromaatilise kiirguse valgusviljakuse fikseeritud arvväärtus Kcd, milleks on 683 väljendatuna ühikus lm·W-1, mis on cd·sr·W-1 või cd·sr·kg-1·m-2·s3, kus kilogramm, meeter ja sekund on määratletud vastavalt h, c ja ΔvCs alusel, SI unit of luminous intensity, equal to the luminous intensity in a given direction, of a source that emits monochromatic radiation of frequency 540 × 1012 Hz and has a radiant intensity in that direction of 1/683 W/sr, SI unit of luminous intensity in a given direction. 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−1 m−2 s3, where the kilogram, metre and second are defined in terms of h, c and ∆νCs.