In reply to Jones Beene's message of Sun, 22 Apr 2012 15:14:40 -0700: Hi Jones,
You are probably correct, but that just shifts the definition of the problem. The question then becomes, "why is density important?" (I'm looking for an answer involving a molecular level analysis.) >Sunlight will cause ignition, with only slight focusing. > >Magnifying glass is sufficient. Be my guest to try it, but stand back... > >This indicates that it is not only energy per photon that is important, but >energetic photon-density per unit area. > > >-----Original Message----- >From: mix...@bigpond.com > >Hi, > >Here's a little conundrum that has troubled me for some time. >Take a cup of gasoline and place it in open sunlight. It will slowly >evaporate. >Bring a flame near it and it will suddenly ignite. > >Why don't the UV rays from sunlight cause ignition? > >Regards, > >Robin van Spaandonk > >http://rvanspaa.freehostia.com/project.html > > Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
