$A$ black body is at $727^\circ C$. It emits energy at a rate which is proportional to

Calculate the radiation power for a sphere whose temperature is $227^{\circ} C$,radius is $2\, m$,and emissivity is $0.8$ (in $W$).

$A$ thin steel square plate of side $10 \ cm$ is heated. The rate of energy emission from the heated plate is $1134 \ W$. What is the temperature of the plate in $K$? (Assume emissivity $\varepsilon = 1$ and $\sigma = 5.67 \times 10^{-8} \ W \ m^{-2} \ K^{-4}$)

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.

Two spherical bodies of radii $r_1$ and $r_2$ have surface temperatures $T_1$ and $T_2$ respectively. They radiate the same power. The ratio $r_1/r_2$ is . . . . . .

$A$ black coloured solid sphere of radius $R$ and mass $M$ is inside a cavity with vacuum inside. The walls of the cavity are maintained at temperature $T_0$. The initial temperature of the sphere is $3T_0$. If the specific heat of the material of the sphere varies as $\alpha T^3$ per unit mass with the temperature $T$ of the sphere,where $\alpha$ is a constant,then the time taken for the sphere to cool down to temperature $2T_0$ will be ($\sigma$ is Stefan-Boltzmann constant).