On Wed, Jul 30, 2014 at 2:57 PM, David Roberson <dlrober...@aol.com> wrote:
A magnifying glass appears to reduce the effective area by a relatively > large amount, although I suspect the concentration is much less that 10,000 > to one. It would be easy to believe that the linear size of the apparent > sun at the focal point is 1/30 th the outside diameter of the glass. This > would appear to concentrate the light by 900 times. > The intensity of the emitted light sounds dangerous to me. Consider that a fresnel lense can easily be used to start a fire with one sun (in contrast to 10,000 suns). If the number is accurate, there may be military applications. Eric
