antudsuunalise valgustugevuse ühik, mille määratlemisel on aluseks võetud 540 × 1012 hertsise sagedusega monokromaatilise kiirguse valgusviljakuse fikseeritud arvväärtus Kcd, milleks on 683 väljendatu, 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 direc, 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 whe