Two different rods $A$ and $B$ are kept as shown in figure. The ratio of thermal conductivities of $A$ and $B$ is

The area of the glass of a window of a room is $10\;{m^2}$ and thickness $2mm$. The outer and inner temperature are ${40^o}C$ and ${20^o}C$ respectively. Thermal conductivity of glass in $MKS$ system is $0.2$. The heat flowing in the room per second will be

Heat is flowing through two cylindrical rods of the same material. The diameters of the rods are in the ratio $1 : 2$ and their lengths are in the ratio $2 : 1$. If the temperature difference between their ends is the same, then the ratio of the amounts of heat conducted through per unit time will be

In the Ingen Hauz’s experiment the wax melts up to lengths $10$ and $25 cm$ on two identical rods of different materials. The ratio of thermal conductivities of the two materials is

The temperature $\theta$ at the junction of two insulating sheets, having thermal resistances $R _{1}$ and $R _{2}$ as well as top and bottom temperatures $\theta_{1}$ and $\theta_{2}$ (as shown in figure) is given by

On heating one end of a rod, the temperature of whole rod will be uniform when