1. The problem statement, all variables and given/known data what is the relation between reflectivity, emissivity, and absorptivity for an opaque material? if an opaque material's reflectivity is 0.075 for solar radiation in the visible range and 0.95 for radiation of a heated surface of 80 degrees Celsius in the far infrared range, what are the corresponding emissivity and absorptivity? 2. The attempt at a solution For an opaque material where the transmitivity is equal to 0, the absorptivity + reflectivity must equal 1. I know for non-opaque materials, the emissivity is equal to the absorptivity, but I do not know any such relationship for opaque materials... For the second part, I am unable to find a starting point. Any help is much appreciated.