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: [email protected] 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
