12.7: A radiation detector has an aperture of area Ad = 106 m and is positioned at a distance of r = 2 m from a surface of area As = 104 m. The angle formed by the normal to the detector and the surface normal is 0 = 25. The surface is at 500 K and is opaque, diffuse, and gray with an emissivity of 0.8. If the surface irradiation is 2500 W/m, what is the rate at which the detector intercepts radiation from the surface? 42220 A,