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
Does Anybody Really Know What Time It Is? Does Anybody Really Know What Time It Is? "Does Anybody Really Know What Time It Is?" is a song by the rock band Chicago. It was included on their 1969 debut album "Chicago Transit Authority" and released as a single in 1970. The song was written and sung by Robert Lamm. The song was not released as a single until two tracks from the band's second album, "Make Me Smile" and "25 or 6 to 4", had become hits. It became the band's third straight Top 10 single, peaking at in the U.S. and No. 2 in Canada. Because the