Question

The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency \('A' \times 10 ^{12}\) hertz and that has a radiant intensity in that direction of \(\frac {1}{'B'}\) watt per steradian. 'A' and 'B' are respectively

(1) 540 and \(\frac {1}{683}\)

(2) 540 and 683

(3) 450 and \(\frac {1}{683}\)

(4) 450 and 683

Answer 1

Correct option is (2) 540 and 683

The candela is the luminous intensity of a source that emits monochromatic radiation of frequency radiation of frequency \(540 \times 10 ^{12}\) Hz and has a radiant intensity in that direction of 1/683 w/sr. It is unit of Candela.