Two identical metallic sheets each behaves like a black body are kept parallel to each other with small separation between them in vacuum. Thermal energy is generated at a constant rate  $P$ in one of the sheets by passing an electric current in it. In steady state, temperature of the other sheet is found to be constant at 300 K. Find the value of  $P$ in kilowatt. (Given area of the plates $A=\frac{{10}^3}{17\times 27}{m}^2$  and  $\sigma =\frac{17}{3}\times {10}^{-8}{\text{\hspace{0.17em}\hspace{0.17em}W/m}}^2{\text{K}}^4$)