A small hemispherical oven is built of two insulating materials. The inner layer is of fire brick, 125 mm thick and outer layer of 85% magnesia, 40 mm thick. The inner surface of the oven is at 8000C and the heat transfer coefficient for the outer surface is 10 W/m2-K. The room temperature is 200C. Calculate the heat loss through hemisphere is the inside radius is 0.6m. The thermal conductivities of fire brick and 85% magnesia are 0.31 and 0.05 W/m-K respectively. Also, calculate the temperature at contact between insulating materials and at the outer surface.