For a surface, the direct and diffuse components of the solar radiation are 400 and 300 $$\frac{W}{m^{2}}$$ and the direct radiation makes 60 deg angle with the normal .If the surface temperature is 300 K and effective sky temperature is 200 K , Calculate net rate of radiation of heat transfer .(Assume solar absorptivity and emmissivity as 0.1 each;For calculation take Stefan Boltzmanns constant as G \times 10^{-8} $$\frac{W}{m^{2}}.K^{4}$$)