One end of a thermally insulated rod is kept at a temperature $T_1$ and the other at $T_2$ . The rod is composed of two sections of length $l_1$ and $l_2$ and thermal conductivities $K_1$ and $K_2$ respectively. The temperature at the interface of the two section is
$\frac{{({K_2}{l_1}{T_1} + {K_1}{l_2}{T_2})}}{{({K_2}{l_1} + {K_1}{l_2})}}$
$\frac{{({K_1}{l_2}{T_1} + {K_2}{l_1}{T_2})}}{{({K_1}{l_2} + {K_2}{l_1})}}$
$\frac{{({K_1}{l_1}{T_1} + {K_2}{l_2}{T_2})}}{{({K_1}{l_1} + {K_2}{l_2})}}$
$\frac{{({K_2}{l_2}{T_1} + {K_1}{l_2}{T_2})}}{{({K_1}{l_1} + {K_2}{l_2})}}$
Figure shows three different arrangements of materials $1, 2$ and $3$ to form a wall. Thermal conductivities are $k_1 > k_2 > k_3$ . The left side of the wall is $20\,^oC$ higher than the right side. Temperature difference $\Delta T$ across the material $1$ has following relation in three cases
Two thin metallic spherical shells of radii ${r}_{1}$ and ${r}_{2}$ $\left({r}_{1}<{r}_{2}\right)$ are placed with their centres coinciding. A material of thermal conductivity ${K}$ is filled in the space between the shells. The inner shell is maintained at temperature $\theta_{1}$ and the outer shell at temperature $\theta_{2}\left(\theta_{1}<\theta_{2}\right)$. The rate at which heat flows radially through the material is :-
Four rods of identical cross-sectional area and made from the same metal form the sides of square. The temperature of two diagonally opposite points and $T$ and $\sqrt 2 $ $T$ respective in the steady state. Assuming that only heat conduction takes place, what will be the temperature difference between other two points
On a cold morning, a metal surface will feel colder to touch than a wooden surface because
The coefficients of thermal conductivity of copper, mercury and glass are respectively $Kc, Km$ and $Kg$ such that $Kc > Km > Kg$ . If the same quantity of heat is to flow per second per unit area of each and corresponding temperature gradients are $Xc, Xm$ and $Xg$ , then