I think that having the ability to quote all of these numbers is where it is interesting to examine what marketers are saying about their products. I have seen so many advertisements where they say "60W!" But it's 60W input power and the output in lumens is mysteriously missing from the packaging. Or the Amazon flashlights which advertise "120,000 lumens" (which at 80 lumens/watt would require 1500W to power), and the reality is that perhaps that's the absolute peak luminous intensity that it is able to reach, and the actual average luminosity is far lower. This lecture really gave me more perspective on how these numbers work.
I think that having the ability to quote all of these numbers is where it is interesting to examine what marketers are saying about their products. I have seen so many advertisements where they say "60W!" But it's 60W input power and the output in lumens is mysteriously missing from the packaging. Or the Amazon flashlights which advertise "120,000 lumens" (which at 80 lumens/watt would require 1500W to power), and the reality is that perhaps that's the absolute peak luminous intensity that it is able to reach, and the actual average luminosity is far lower. This lecture really gave me more perspective on how these numbers work.