Candela was chosen so that the new definition would precisely match the old definition. Although the candela is now defined in terms of the second (an SI base unit) and the watt (a derived SI unit), the candela remains a base unit of the SI system, by definition. If a source emits a known luminous intensity "I" (in candelas) in a well-defined cone, the total luminous flux "Φ" in lumens is given by where "A" is the "radiation angle" of the lamp—the full vertex angle of the emission cone. For example, a lamp that emits 590 cd with a radiation angle
Rosario Candela as well as social cynosure." Born in Montelepre, Sicily in 1890, Candela immigrated to New York in 1906. He returned to Sicily after his arrival to study there and returned to the US in 1909. His father was Michele Candela, a plasterer, and his mother was Josephine Pizzurro. He gained admission to the Columbia University School of Architecture and graduated in 1915. Keenly aware of his talent, he went so far as to erect a velvet rope around his drafting table to prevent other students from copying his designs. After graduation, Candela worked briefly as a draftsman for the Palermo-born