- The fundamental SI unit of luminous intensity. Formerly, it was defined in various manners, ranging from the light of a certain type of candle under particular conditions, to more recently as a given proportion of the radiating power of a blackbody under specific conditions. It is currently defined as the luminous intensity of a light source emitting monochromatic radiation in a given direction at a frequency of 540 terahertz, with a power of 1/683 watt per steradian in the specified direction. Its symbol is cd. This term was formerly known as candle, international candle, standard candle, or new candle.
Not what you were looking for?