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
Félix Candela Perpignan Concentration camp in Perpignan, France until the end of the war in 1939. Candela had fought against Franco; therefore he could not stay in the new Spain as long as Franco was the head of state. After his name was selected with a few hundred other prisoners, Candela was put onto a ship bound for Mexico, where he would start his career. Candela married Eladia Martin when he moved to Mexico from Spain; there, they raised a family. In his early life, Felix was active in sports, particularly rugby and skiing. Candela worked very hard during his lifetime to