A wall consists of alternating blocks of length $d$ and coefficient of thermal conductivity $K_{1}$ and $K_{2}$ respectively as shown in figure. The cross sectional area of the blocks are the same. The equivalent coefficient of thermal conductivity of the wall between left and right is
$\frac{{2{K_1}{K_2}}}{{{K_1} + {K_2}}}$
$\frac{{{K_1} + {K_2}}}{3}$
$\;\frac{{{K_1}{K_2}}}{{2({K_1} + {K_2})}}$
$\;\frac{{{K_1} + {K_2}}}{2}$
The dimensional formula for thermal resistance is
In the following figure, two insulating sheets with thermal resistances $R$ and $3R$ as shown in figure. The temperature $\theta$ is ...... $^oC$
Four conducting rods are joined to make a square. All rods are identical and ends $A, B$ and $C$ are maintained at given temperatures. choose $INCORRECT$ statement for given arrangement in steady state. (value of $\frac {KA}{L}$ is $1\frac{J}{{{S^o}C}}$ , symbols , have their usual meaning)
The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity $K$ and $2K$ and thickness $x$ and $4x$ , respectively are $T_2$ and $T_1$ ($T_2$ > $T_1$). The rate of heat transfer through the slab, in a steady state is $\left( {\frac{{A({T_2} - {T_1})K}}{x}} \right)f$, with $f $ which equal to