申論題

4. The net radiative heat flux at the surface of an opaque medium can be evaluated using the rollowing equation if the absorptivity of the medium is cqual to its emissivity
  
where E is the emissivity, o the Stefan-Boltzmann constant, Ts the surface temperature and J the radiosity. This equation seems to predict a very large radiative heat flux for a blackbody that (5%) hasε = 1. Please explain.