Just try to answer the question. The steradians of a 20 degree diameter cone could be calculated by the integration on slide 17, with FI from 0 to 10Pi/180 and Theta from 0 to 2Pi. The sr = 0.191pi. So the Intensity = 815 lumens / 0.191 pi sr = 1359 candelas.
archshift
You can see here how LEDs can be so much more efficient per lumen; incandescent lights produce a huge amount of infrared light which humans can’t see:
avinashnandakumar
Hey @archshift, that makes sense that incandescent emissions produce a lot of light that we can't see, I'm curious to see where LED's fall on that graph, would they be completely contained by the visible spectrum?
aparikh98
This site has some more information about the spectrums of various lights
Just try to answer the question. The steradians of a 20 degree diameter cone could be calculated by the integration on slide 17, with FI from 0 to 10Pi/180 and Theta from 0 to 2Pi. The sr = 0.191pi. So the Intensity = 815 lumens / 0.191 pi sr = 1359 candelas.
You can see here how LEDs can be so much more efficient per lumen; incandescent lights produce a huge amount of infrared light which humans can’t see:
Hey @archshift, that makes sense that incandescent emissions produce a lot of light that we can't see, I'm curious to see where LED's fall on that graph, would they be completely contained by the visible spectrum?
This site has some more information about the spectrums of various lights
https://www.comsol.com/blogs/calculating-the-emission-spectra-from-common-light-sources/
@E-BAO I'm confused. How did you get 0.191pi steradians? Why did you integrate fi from 0 to 10pi/180?
+1: How do we calculate the solid angle of a cone?
Wikipedia says:
Ω=2π(1−cosθ)sr
So when I plug in:
Ω=2π(1−cos(10∘∗180pi))sr=0.0954sr
Suspiciously, this answer is half of E-BAO's.