This is killing me because I used to know how to solve this problem, and I can't remember how to make it work. Its been too long since I took a physics course. I will be placing some plastic sheeting near a 1000W lamp. I want to calculate how hot the sheeting is going to get, to make sure its not going to melt or catch fire. I know that this involves the boltzman law, j = σT^4, but I can't figure out how to make it work. Parameters are the following: --at 20 cm distance, 400W/m^2 --at 30cm distance, 250 W/m^2 --the sheeting passes 90% of light, which is basically the same as having an albedo of 90%, right? its not as simple as plugging the 400 or the 250 W/m^2 into the left hand side of the j = σT^4 and solving for T -- i get answers that don't make sense when I do this. help much appreciated! EDIT: This is not a homework problem, but seems a little bit pedestrian for this forum. If it belongs in a homework subforum, I'd appreciate if a mod could move it.