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 many of his peers, Candela didn’t show intellectual or aesthetic efforts in school. He didn’t even like pure mathematics. When Candela was a student in Madrid, the schools taught the theory of elasticity where Candela assisted the professors and even tutored other students. His studies ended very quickly when the Spanish civil war began in 1936. When Candela returned to Spain to fight, he sided with the republic and fought against Franco. Candela became a Captain of Engineers for the Spanish republic after a short period of time. Unfortunately, while participating in the civil war, Candela was imprisoned in the