 Units of luminous intensity

The unit of luminous intensity is the candela (symbol: cd). The candela is one of the seven base units in the International System of Units (SI). It is defined as the luminous intensity in a given direction of a source that emits monochromatic radiation of frequency 540 × 10^12 hertz and has a radiant intensity in that direction of \( \frac{1}{683} \) watts per steradian.