The dimensional formula for thermal resistance is

Two conducting rods $A$ and $B$ of same length and cross-sectional area are connected $(i)$ In series $(ii)$ In parallel as shown. In both combinations,a temperature difference of $100^{\circ}C$ is maintained. If the thermal conductivity of $A$ is $3K$ and that of $B$ is $K$,then the ratio of heat current flowing in the parallel combination to that flowing in the series combination 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 of equal length and diameter have thermal conductivities $3$ and $4$ units respectively. If they are joined in series, the thermal conductivity of the combination would be

Two rods $A$ and $B$ of the same cross-sectional area $A$ and length $l$ are connected in series between a source $(T_1 = 100^{\circ}C)$ and a sink $(T_2 = 0^{\circ}C)$ as shown in the figure. The rods are laterally insulated. The thermal conductivities of rods $A$ and $B$ are $3K$ and $K$ respectively. The ratio of the thermal resistance of rod $A$ to that of rod $B$ is:

In the following figure,two insulating sheets with thermal resistances $R$ and $3R$ are shown. The temperature $\theta$ at the interface is ...... $^oC$.