A circular disc heater 0.2 m in diameter is exposed to ambient air at 25°C. One side is insulated and the other side is maintained at 130°C. Find heat transfer when disc is placed: (i) horizontally...

A circular disc heater 0.2 m in diameter is exposed to ambient air at 25°C. One side is insulated and the other side is maintained at 130°C. Find heat transfer when disc is placed: (i) horizontally and hot surface facing up, (ii) horizontally with hot surface facing down, and (iii) vertical.