A long metal sheet that can be approximated as a blackbody is being
A long metal sheet that can be approximated as a blackbody is being conveyed through a water bath to be cooled. In order to prevent thermal burn on people handling the sheet it must exit the water bath at a temperature below 45C. A radiometer is placed normal to and at a distance of 0.5 m from the sheet surface to monitor the exit temperature. The radiometer receives radiation from a target area of 1 cm2 of the metal sheet surface. When the radiometer detects that the metal sheet temperature is not below 45C an alarm will go off to warn that the sheet is not safe to touch. Determine the irradiation on the radiometer that the warning alarm should be triggered.