A black nonreflective plane at temperature T₀ is parallel to a black plane at temperature T. The net energy flux density in vacuum between the two planes is F₀ = σ (T₀⁴ - T⁴), where σ is the Stefan-Boltzmann constant. A third black plane is inserted between these two planes and is allowed to come to an equilibrium temperature T₁.
Find T₁ in terms of T₀ and T and the net energy flux density between the original two planes.
