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 as much information as he could find. From this, he started questioning the behaviour of reinforced concrete with the elastic assumptions and concluded they are in total disagreement with each other. Candela has said on more than one occasion that the analysis of a structure is a sort of "hobby" to him. Félix Candela worked as an architect upon his arrival in Mexico until 1949 when he started to engineer many concrete structures utilizing his well-known thin-shell design. Candela did most of his work in Mexico throughout the 1950s and into the late 60s. He was responsible for more than