$A$ rod $CD$ of thermal resistance $10.0 \; K/W$ is joined at the middle of an identical rod $AB$ as shown in the figure. The ends $A$,$B$,and $D$ are maintained at $200^{\circ}C$,$100^{\circ}C$,and $125^{\circ}C$ respectively. The heat current in $CD$ is $P$ watt. The value of $P$ is ... .

Two rods $A$ and $B$ of different materials but same cross-section are joined as shown in the figure. The free end of $A$ is maintained at $100^{\circ}C$ and the free end of $B$ is maintained at $0^{\circ}C$. If $l_2 = 2l_1$,$K_1 = 2K_2$ and the rods are thermally insulated from the sides to prevent heat losses,then the temperature $\theta$ of the junction of the two rods is ........ $^{\circ}C$.

Two rods of the same length and material transfer a given amount of heat in $12 \ s$ when they are joined end to end. But when they are joined lengthwise parallel to each other,they will transfer the same amount of heat under the same conditions in a time of: (in $s$)

Why do people prefer to give a layer of sand or foam insulation on ceilings made of concrete?

Two rods of same material have same length and area. The heat $\Delta Q$ flows through them for $12 \, \text{minutes}$ when they are joined in series. If now both the rods are joined in parallel,then the same amount of heat $\Delta Q$ will flow in ........ $\text{minutes}$.

$A$ wall consists of two layers $A$ and $B$. Both layers have the same thickness but are made of different materials. The thermal conductivity of $A$ is twice that of $B$. In the steady state,the temperature difference across the two ends of the wall is $36^{\circ}C$. What is the temperature difference across the two ends of layer $A$ in $^{\circ}C$?