$A$ thermos flask is polished well.

If $e_\lambda$ and $a_\lambda$ are the emissive power and absorptive power of a body respectively,and $E_\lambda$ is the emissive power of a perfectly black body,what is the relation according to Kirchhoff's law?

$A$ sphere,a cube,and a thin circular plate,all made of the same material and having the same mass,are initially heated to a temperature of $1000^{\circ}C$. Which one of these will cool first?

Thermal radiation travels at the speed of . . . . . . .

Surface temperature of the sun is of the order of $K$.

$A$ spherical body of emissivity $e = 0.6$ placed inside a perfect black body is maintained at temperature $T$. The energy radiated per second by the body will be: