Question

Figure (1), (2), (3) shows three different arrangements of materials 1, 2 and 3 to form a wall. Thermal conductivities are K₁ > K₂ > K₃. The left side of the wall is 20^oC higher than the right side. Temperature difference DT across the material 1 has following relation, in three cases:

• A. DT_a > DT_b > DT_c
• B. DT_a = DT_b = DT_c
• C. DT_a = DT_b > DT_c
• D. DT_a = DT_b < DT_c

Answer 1

Answer: (B)

DT_a = DT_b = DT_c

Answer 2

All are in series therefore current remains same. Hence temperature difference = (current × thermal resistance) are equal for every case.