GATE 2022 MT – Question 54
A block consists of Materials I and II with identical cross-sections and equal thicknesses 25 mm, as shown. Bottom and top temperatures are 435 K and 400 K. Conductivities are $k_I=50$ and $k_{II}=200$ W m$^{-1}$ K$^{-1}$. For purely steady conductive heat transfer, the interface temperature is ______ K (nearest integer).
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 406 to 408
Explanation
Equal thickness and area give $R_I/R_{II}=k_{II}/k_I=4$. The total temperature drop 35 K splits into 28 K across I and 7 K across II. Interface temperature is $435-28=\boxed{407}$ K.