Thread: Is all reading good?
View Single Post
Old 09-23-2009, 09:43 AM   #146
jbjb
Somewhat clueless
jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.jbjb ought to be getting tired of karma fortunes by now.
 
Posts: 773
Karma: 9999999
Join Date: Nov 2008
Location: UK
Device: Kindle Oasis
Quote:
Originally Posted by ahi View Post
Couldn't you just flip it around?

- Ahi
No - a concave lens is thinner in the middle than at the edges. Flip it around and it's still thinner in the middle than at the edges.

A concave lens is diverging - it will spread out the light. A convex lens is converging, and will concentrate the sunlight onto a point, which is what is needed to start the fire.

/JB
jbjb is offline   Reply With Quote