What is the temperature of the steel-copper junction in the steady state of the system shown in Fig. 10.15 when the length of the steel rod is 15.0 cm, the length of the copper rod is 10.0 cm, the temperature of the furnace is 300 °C, and the temperature of the other end is 0 °C, with the area of cross section of the steel rod being twice that of the copper rod and using the thermal conductivity values of steel (50.2 J ${{s}^{-1}}$ ${{m}^{-1}}$ ${{K}^{-1}}$) and copper (385J ${{s}^{-1}}$ ${{m}^{-1}}$ ${{K}^{-1}}$)?