The Candela (cd) is the base unit of the luminous intensity of a source in a given direction in the International System (SI) of Units that is the luminous power per unit solid angle emitted by a point light source in a particular direction.
Reference Definition by NIST: The candela, symbol cd, is the 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 x 1012 Hz, Kcd, to be 683 when expressed in the unit lm W-1, which is equal to cd sr W-1, or cd sr kg-1 m-2 s3, where the kilogram, meter and second are defined in terms of h, c and ΔνCs.
Related Definitions in the Project: The Property and Unit
