The surface of a thermos flask is kept shiny because:

At a certain temperature for a given wavelength,the ratio of the emissive power of a body to the emissive power of a black body in the same circumstances is known as:

One likes to sit under sunshine in the winter season,because

$A$ perfect black body is ........

$A$ solid cylinder of length $L$ and radius $r$ is heated up to the same temperature as that of a cube of edge length $a$. If both have the same material,volume,and are allowed to cool under similar conditions,then the ratio of the amount of radiation emitted will be (Neglect radiation emitted from the flat surfaces of the cylinder).

$A$ 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: