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

by Panthera Leo
Tags: 1000, celcius, focus, lens, light, reach
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Panthera Leo
#1
Aug15-11, 06:33 PM
P: 110
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 :)
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CJames
#2
Aug15-11, 07:19 PM
CJames's Avatar
P: 355
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
#3
Aug15-11, 07:25 PM
Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,568
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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