Stupid science

[vadimax]

Who might check how much lumens are needed to start a fire with a flashlight and a magnifying glass?

 

[GordoJones88]

 

[ven]

:laughing: i knew it!!!!!!!!!!!!!!!

Not sure on the lumens, more on the reflector/lens/asperic being used and how concentrated the hot spot is. No need for a magnifying glass though!

http://www.candlepowerforums.com/vb/showthread.php?417513-LED-FIRE-STARTER-Flashlight!!!

 

[bykfixer]

Why all the pyro threads lately?

 

[jorn]

Visible light itself is not heat. I think the heat is more of a bi product. Light from halogen got more heat than light from a led, so its hard to tell how many lumens you need. Example.The old cars got halogen, and the glass on the headlamps never froze. If it was covered in snow, it melted. Then hid came and problems with ice film on the headlamp arrived (atleast in the arctic part of the world). Now the led made the problem even worse...

 

[vadimax]

Ok, checked it myself. The primary problem is to get a quality magnifying glass that itself renders the idea useless. Crap glass just cannot collect a flashlight emission in one focal point. Even TN32 at its declared 1702 lm just managed to make a black carton rather warm in 2 minutes, but nothing more. Major effect was hurting my eyes with reflection from the black surface :thinking::fail:

 

[eekazum]

I agree with jorn about heat being a byproduct of light.
The reverse of his example are those parabolic heaters that produce a warm glow but puts out a pretty intense beam of heat. I wonder in you can somehow "magnify" that to a single focal point to start fires miles away like a magic trick. Hmmm...
With these led flashlights tho, you are better off trying to burn something using the heatsink instead.