The temperature of a spherical black body is inversely proportional to its radius. If its radius is doubled,then the power radiating from it will be

The unit of Stefan-Boltzmann's constant $(\sigma)$ is:

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

Radiation from a black body at the thermodynamic temperature $T_1$ is measured by a small detector at distance $d_1$ from it. When the temperature is increased to $T_2$ and the distance to $d_2$,the power received by the detector is unchanged. What is the ratio $d_2/d_1$?

The ratio of the radii of two spheres made of the same material is $1:4$ and the ratio of their temperatures is $2:3$. The ratio of the energy emitted by the spheres per second will be:

$A$ solid cylinder of radius $r_1=2.5 \ cm$,length $l_1=5.0 \ cm$ and temperature $40^{\circ}C$ is suspended in an environment of temperature $60^{\circ}C$. The thermal radiation transfer rate for the cylinder is $1.0 \ W$. If the cylinder is stretched until its radius becomes $r_2=0.50 \ cm$,the thermal radiation transfer rate is changed to (in $W$)