Q 11-10-074JEE MainJEE Main 2022 (24 Jun, Shift 1)Medium
Two metallic blocks $M_1$ and $M_2$ of same area of cross-section are connected to each other (as shown in figure). If the thermal conductivity of $M_2$ is $K$ then the thermal conductivity of $M_1$ will be: [Assume steady state heat conduction]
Answer: (B) $8K$
In steady state the same heat current flows through both blocks:
$$\frac{K_1A(100-80)}{16} = \frac{KA(80-0)}{8}\ \Rightarrow\ \frac{20K_1}{16} = 10K\ \Rightarrow\ K_1 = 8K$$
Solution by Sreeraj P, M.Sc Physics