Question

The diagram below shows rods of the same size of two different materials P and Q placed end to end in thermal contact and heavily lagged at their sides. The outer ends of P and Q are kept at 0⁰C and 100⁰C, respectively. The thermal conductivity of P is four times that of Q. What is the steady-state temperature of the interface ?

• A. 20⁰C
• B. 75⁰
• C. 25⁰C
• D. 80⁰C

Answer 1

Answer: (A)

20⁰C

Answer 2

$\frac{4K(T–0)}{L}$= $\frac{K(100–T)}{L}$