A spherical aluminum shell of inside diameter \(D=2 \mathrm{~m}\) is evacuated and is used as a radiation test chamber. If the inner surface is coated with carbon black and maintained at \(800 \mathrm{~K}\), what is the irradiation on a small test surface placed in the chamber? If the inner surface were not coated and maintained at \(800 \mathrm{~K}\), what would the irradiation be?