GATE2016-3-42

Question

Two large parallel plates having a gap of $10 \: mm$ in between them are maintained at temperatures $T_1 = 1000  \: K$ and $T_2 = 400 \: K$. Given emissivity values, $\epsilon _1 = 0.5$, $\epsilon _2=0.25$ and Stefan-Boltzmann constant $\sigma =5.67 \times 10^{−8} \: W/m^2-K^4$, the heat transfer between the plates (in $kW/m^2$) is __________