Consider two large (infinite) parallel planes that are diffuse-gray with temperatures and emissivities of T₁, ?₁ and T₂, ?₂. Show that the ratio of the radiation transfer rate with multiple shields, N, of emissivity ?_s to that with no shields, N = 0 is, where q_{12, N} and q_{12, O} represent the radiation heat transfer rates for N shields and no shields, respectively.

(l/e, + l/e, - 1] 412N 4120 (lie, + le; - 11+ N(2/e, -1]