Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in $20$ minutes and $40$ minutes respectively. The ratio of thermal conductivities of the materials is

Ice formed over lakes has

$A$ wall consists of two layers $A$ and $B$. The two layers have the same thickness but are made of different materials. The thermal conductivity of $A$ is twice that of $B$. Under steady-state conditions,the temperature difference between the two ends is $36 ^\circ C$. The temperature difference across the two surfaces of $A$ is .......... $^\circ C$.

In a steady state,the temperatures at the ends $A$ and $B$ of a $20\,cm$ long rod $AB$ are $100\,^{\circ}C$ and $0\,^{\circ}C$ respectively. The temperature of a point $C$ at a distance of $9\,cm$ from $A$ is....... $^{\circ}C$

Consider two rods $1$ and $2$ of same length $L$. They have different specific heats $(C_1, C_2)$, thermal conductivities $(K_1, K_2)$ and area of cross-section $(A_1, A_2)$ respectively. Both the rods have temperatures $(T_1, T_2)$ at their ends. If their rate of loss of heat due to conduction is equal, then

Two rods of the same length and same cross-sectional area are joined in series. The temperatures at the two ends are as shown in the figure. As we move along the rod,the temperature variation is as shown in the following graph.