3.- Radiation: A basic problem In the previous problem the radiator was a "convector". We now add the effect of radiation to the heat transferred by the device. As a parallel transfer mechanism, heat is transferred by radiation from the plate at 60C to the walls of the enclosure, which are found at 20C. Find the heat that the plate transfers by radiation to those walls. Consider both the plate and the walls to be black bodies. Also calculate the total heat leaving the plate, adding convection and radiation.