It takes $10$ minutes to cool a liquid from $61^{\circ} C$ to $59^{\circ} C$. If room temperature is $30^{\circ} C$ then time taken in cooling from $51^{\circ} C$ to $49^{\circ} C$ is .......... $min$ 

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  ......... $^oC$

The radiant energy from sun incident normally at the surface of earth is $20\, kcal/m^2-min$. What would have been the radiant energy incident normally on the earth if the sun had a temperature twice of the present one ......... $kcal/m^2-min$

The rate of emission of radiation of a black body at $273^o C$ is $E$, then the rate of emission of radiation of this body at $0^o C$ will be

A rod of length $2m$ at $0^o C$ and having expansion coefficient $ \alpha  = (3x + 2) \times 10^{-6}$ $ ^o C^{-1}$ where $x$ is the distance (in $cm$) from one end of rod. The length of rod at $20^o C$ is ......... $m$

The temperature of body is increased from $27\,^oC$ to $127\,^oC$ the radiation emitted by it increases by a factor of