Star$ S_1$ emits maximum radiation of wavelength  $420$ $nm$ and the star $S_2$ emits maximum radiation of wavelength $560 \,\,nm$, what is the ratio of the temperature of $S_1$ and $S_2$ :

The intensity of radiation emitted by the Sun has its maximum value at a wavelength of $510\,\, nm$ and that emitted by the North Star has the maximum value at $350\,\, nm$. If these stars behave like black bodies then the ratio of the surface temperature of the Sun and the North Star is

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  ......... $^oC$

In a composite rod, when two rods of different lengths $l_1$ and $l_2$ and of the same cross-sectional area are joined from end to end then if $K$ is the effective coefficient of thermal conductivity,  the value of $(l_1 + l_2)/K$ is

A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents. Which of the following curves correctly represents the rate of cooling

Two rods having same area are used to connect two reservoirs at temperature $100\,^oC$ and $0\,^oC$ as shown. The temperature of junction is $70\,^oC$. If the rods are now interchanged, the temperature of junction will be  ......... $^oC$