An opaque body, with the hemispherical total reflectivity r = 0.15, reflects diffusely. Determine the intensity Lref of the reflected radiation and the absorbed radiative power per area for an...

An opaque body, with the hemispherical total reflectivity r = 0.15, reflects diffusely. Determine the intensity Lref of the reflected radiation and the absorbed radiative power per area for an irradiance E = 800W/m².

An enclosure is kept at a constant temperature. Radiation enters from outside through a small, circular opening of diameter d = 5.60 mm; the radiation flow is Φ = 2.35W. What is the temperature of the enclosure walls?