| Compact fluorescent - you know, the spiral ones. The light the bulbs give out are measured in lumens. 1 lumen concentrated on a surface area of 1 foot squared is one footcandle. Light radiates from a light source with a spherical equi-intensity pattern. The surface area of a sphere is 4(pi)r^2 . So in order for a 1 lumen bulb (point source) to provide 1 footcandle to an object, the object must be ... (1/(4(pi)r^2) = 1 , r^2 = 1/(4(pi)) , r= 1/(2*sqrt(pi)) , r= .282 ft , = 3.4 in) 3 inches away. Hehe
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- Aaron  |