A cylindrial rod with ffectiveness 0.7 of 50 mm diameter is maintained at 1000 C by an electric resistance heating and is kept in a room, the wall with effectiveness 0.6 at 15 C. Determine (a) the energy which must be supplied per meter length of the rod, (b) the energy supplied to the rod per meter length. If an insulated half circular reflector of 0.45 m diameter is placed around the rod.