$A$ black body is at a temperature $300 K$. It emits energy at a rate,which is proportional to

Solar constant $(S)$ depends upon the temperature of the Sun $(T)$ as ........

Assuming the sun to have a spherical outer surface of radius $r$,radiating like a black body at temperature $t^{\circ} C$,the power received by a unit surface (normal to the incident rays) at a distance $R$ from the centre of the sun is,where $\sigma$ is the Stefan's constant.

$A$ black sphere has radius $R$ whose rate of radiation is $E$ at temperature $T$. If the radius is made half and the temperature is made $4T$,the rate of radiation will be: (in $E$)

$A$ black body is heated from $7\,^oC$ to $287\,^oC$. The ratio of radiation emitted is

The outer surface of a star in the form of a sphere radiates heat as a black body at temperature $T$. The total radiant energy per unit area,normal to the direction of incidence,received at a distance $R$ from the center of a star of radius $r$ is $(R > r)$ ($\sigma =$ Stefan's constant).