How big should a lens be to focus enough light to reach 1000 Celcius???

Panthera Leo

I was wondering how big should a glass lens be to focus enough light to produce a temperature of about 1000 celcius at its foci???

What if the lens was made up of sth with higher refractive index, doesn't this reduce the size of lens?

A rough guess will do... I am just curious

Thanks in advance :)

CJames

Take a look at this thread:

http://www.physicsforums.com/showthread.php?t=315719

Also have a look into fresnel lenses:

http://en.wikipedia.org/wiki/Fresnel_lens

HallsofIvy

So we have yet another post (three or four of then today) that seems to assume that a specific amount of energy translates to a specific temperature. That is NOT true.

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Panthera Leo	How big should a lens be to focus enough light to reach 1000 Celcius??? I was wondering how big should a glass lens be to focus enough light to produce a temperature of about 1000 celcius at its foci??? What if the lens was made up of sth with higher refractive index, doesn't this reduce the size of lens? A rough guess will do... I am just curious Thanks in advance :)

CJames	Take a look at this thread: http://www.physicsforums.com/showthread.php?t=315719 Also have a look into fresnel lenses: http://en.wikipedia.org/wiki/Fresnel_lens

HallsofIvy Recognitions: Gold Member Science Advisor Staff Emeritus	So we have yet another post (three or four of then today) that seems to assume that a specific amount of energy translates to a specific temperature. That is NOT true.