申論題

8. The figure shows the cross section of a two-layer wall. The temperatures for the left face, interface, and right face are T₁ = 30 °C, T₂ = 20 °C, and T₃ = -10 °C. Layer 1 has thickness 0.20 m; layer 2 has thickness 0.60 m. What is the thermal conductivity k of layer 2 in terms of that of layer 1? That is, what goes in the blank here: k₂ =_____ k₁?