The 50-mm peephole of a large furnace operating at 450°C is covered with a material having ? = 0.8 and p = 0 for irradiation originating from the furnace. The material has an emissivity of 0.8 and is opaque to irradiation from a source at room temperature. The outer surface of the cover is exposed to surroundings and ambient air at 27°C with a convection heat transfer coefficient of 50 W/m2 ? K. Assuming that convection effects on the inner surface of the cover are negligible calculate the heat loss by the furnace and the temperature of the cover.