GATE MT 2021 Q55. A solid sphere (0.5 m radius) is enclosed within a larger hollow sphere (1 m radius), as shown in figure. The radiation exchange takes place between the outer surface (surface 1) of the small sphere and the inner surface (surface 2) of the bigger sphere. The value of the view factor, F22 is: (round off to 2 decimal places). Given: View factor (Fij) is the fraction of the radiation leaving surface i that is intercepted by surface j.