Why does LED brightness decrease with temperature?
In the above question
a)constant power supplying to LED, means no variations in power ok.
So In generally materials characteristics effects with temperature.
If Heat increases beyond the particular material properties,resistance increases causing oppose to flow of electrons ---when electrons decreases, Light (Brightness) gets low.
for fun only----LED using in AC Room gets very little effect than non AC room with Temp high.
Sorry i am not good yet english.