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 45°C. 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 45°C, 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.