Metric (SI) unit
of luminous intensity that measures
the brightness of the light itself and not the illuminance (the amount
of light falling on an object
which is measured in lux). One candela represents monochromatic radiation
at a frequency
of 540 terahertz (THz) and radiant intensity of 1/683 watt per steradian. It replaces the older candle, standard
candle, and international candle units.