Four rods of the same material and having the same cross-section and length have been joined as shown in the figure. The temperature of the junction of the four rods will be ............... $^{\circ}C$.

Three rods $AB, BC$ and $AC$ having thermal resistances of $10 \text{ units}, 10 \text{ units}$ and $20 \text{ units}$ respectively,are connected as shown in the figure. Ends $A$ and $C$ are maintained at constant temperatures of $100^{\circ}C$ and $0^{\circ}C$ respectively. The rate at which the heat is crossing junction $B$ is . . . . . . $units$.

Three rods $A, B,$ and $C$ of thermal conductivities $K, 2K$ and $4K$,cross-sectional areas $A, 2A$ and $2A$ and lengths $2l, l$ and $l$ respectively are connected as shown in the figure. If the ends of the rods are maintained at temperatures $100\,^oC$,$50\,^oC$,and $0\,^oC$ respectively,then the temperature $\theta$ of the junction is

$A$ wall has two layers $A$ and $B,$ each made of different material. Both the layers have the same thickness. The thermal conductivity for $A$ is twice that of $B$ and under steady condition,the temperature difference across the wall is $36\,^{\circ}C.$ The temperature difference across the layer $A$ is....... $^{\circ}C$

Two rods having the same cross-sectional area are used to connect two reservoirs at temperatures $100\,^{\circ}C$ and $0\,^{\circ}C$ as shown. The temperature of the junction is $70\,^{\circ}C$. If the rods are now interchanged,the temperature of the junction will be ......... $^{\circ}C$.

Two rods of the same length and material transfer a given amount of heat in $12 \text{ s}$ when they are joined end-to-end. If they are joined lengthwise, in how many seconds will they transfer the same amount of heat under the same conditions (in $\text{ s}$)?