Need help finding the net rate of emission of radion of the object?

A spherical object of radius 0.1 m and emissivity 0.4 is at a temperature of 75 degree celcius. Its environment is at a temperature of 13 degree celcius. Calculate the net rate of emission of radiation of the object.Need help finding the net rate of emission of radion of the object?
If 75C is temperature of the outer surface, then deltaT between the surface and the surroundings is 62K .





Net rate of emission = (5.6704 x 10^-8 W/m^2.K^4) (0.4) 4(pi)(r^2) (deltaT^4)





Radiation emission = (2.26816 x 10^-8 W/m^2.K^4) (12.57 cm^2) (10^-4m^2/1cm^2) (63K^4)





Rad emission = 0.5642 Watts








Edit:


If the heat is 75C on the surface, then in the center of mass it will be:





Peak central temperature = (0.5642 Watts) (0.1m) / (Thermal conductivity of sphere material) (12.6cm^2) + 75C





PCT = 75C + 0.04478(k)


k = thermal conductivity





So if it was:





(Materal / Peak Central Temperature)





Lead / 76.6C


Iron / 78C


Copper / 93C





Helium balloon / 75.007C


Glass / 75.048C