Just a bit curiousity:
I am very interested in physics, and found that it's to a certain extent a likeness between a rocket and a light: if an incan corresponds to a rocket standing upright, a LED corresponds to a rocket placed laid down on a wagon with wheel, for example, on a railway.
Like the incan will not glow at all as long the current is too low for the given incan, the upright standing rocket will not lift as long the thrust is lower than the weight. The rocket engine may produce miljons of horsepowers but these will be totally spoiled in the same way all the watts of the incan are spoiled.
The LED then corresponds to the rocket placed laid down on the railway. This will require only some few percents thrust of the rockets weight to make it moving.
The LED-light output/laid down rocket acceleration will in this case be more related to the power than with the incan-light output/standing rocket acceleration.
Surely the simile isn't complete, but there are some likenesses...
Edit: I see that when Kelvin is mentioned it's called degrees Kelvin. When I studied physics at school I learned that Kelvin, contrary to Celsius, are not degrees but just Kelvin.
Regards, Patric