To maintain a circular disc at 1000 K, an electrical heater is supplying heat from the backside. The disc is positioned coaxial to a conical shape having the same outer diameter as 0.6 meter. The backside of the cone is well insulated. The disc is gray with emissivity equal to 0.5. The top cone region has emissivity equal to 1. The surrounding can be considered a large, evacuated black enclosure whose walls are at 300 K. You may neglect convection in this problem. (a) What is the view factor from the top cone to the bottom circular plate? What is the view factor from the bottom circular plate to the surrounding?

(b) What is the electrical power that would be required to maintain the disc at 1000 K?