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 enrolled in La Escuela Superior de Arquitectura (Madrid Superior Technical School of Architecture), graduating in 1935; at which time Candela traveled to Germany to further study architecture. Early after he started classes, he developed a very keen sense of geometry and started teaching other students in private lessons. In his junior year, his visual intelligence and his descriptive geometric and trigonometric talent helped him catch the eye of Luis Vegas. Vegas was his material strength professor, and gave Candela the honorary title of “Luis Vegas’ Helper”. While “helping” Vegas, Candela entered many architecture competitions and won most of them. Unlike