A wall has two layers $A$ and $B$ , each made of a different material. Both the layers have the same thickness. The thermal conductivity of the material of $A$ is twice that of $B$ . Under thermal equilibrium, the temperature difference across the wall is $36\,^oC$. The temperature difference across the layer $A$ is  ......... $^oC$

Two rods of same length and same area of cross section are joined

Temperature of two ends are as shown in figure. As we move along the rod, temperature are as shown in following

Gravitation force is required for

A spherical body of emissitivity $e = 0.6$ placed inside a perfect black body is maintained at temperature $T$, then the energy radiated per second will be

A black body at a high temperature $T\, K$ radiates energy at the rate $E\, watt/m^2$ ; when the temperature falls to $(T/2)\, K$ the radiated energy will be

A black body at a high temperature $T\, K$ radiates energy at the rate $E\, watt/m^2$ ; when the temperature falls to $(T/2)\, K$ the radiated energy will be