Question

Two different rods $A$ and $B$ are kept as shown in the figure.

The variation of temperature of different cross-sections is plotted in the graph shown in the figure. Find the ratio of thermal conductivities of $B$ to $A$.

Answer 1

$\because\left(\frac{\Delta Q}{\Delta t}\right)_{A}=\left(\frac{\Delta Q}{\Delta t}\right)_{B}$
$\therefore \frac{-K_{A} A(100-70)}{30}=\frac{K_{B} A(70-35)}{70}$
$\Rightarrow K_{A}=\frac{K_{B}}{2}$
$\Rightarrow \frac{K_{B}}{K_{A}}=2$