A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when A)CPA CPB B)CPA

Question

A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when A)CPA > CPB B)CPA < CPB C)kA < 0.5 kB D)kA >2 kB

Quizplus · Accepted Answer

The temperature difference across a plate in steady state depends on the thermal conductivity and thickness of the plate, not on the specific heat capacity. For the temperature difference across plate A to be greater than that across plate B, despite B being thicker, A must have a lower thermal conductivity. Therefore, kA < 0.5 kB is the condition that would lead to a greater temperature difference across the thinner plate A.

A Composite Wall Consists of Two Plates a and B