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

The rate of radiation by a black body is $R$ at temperature $T$. Another body has the same area but an emissivity of $0.2$ and a temperature of $3T$. Its rate of radiation is:

Star $A$ has radius $r$ and surface temperature $T$,while star $B$ has radius $4r$ and surface temperature $T/2$. The ratio of the power radiated by the two stars,$P_A : P_B$,is:

The temperatures of two bodies $A$ and $B$ are $727^{\circ}C$ and $127^{\circ}C$. The ratio of the rate of emission of radiations will be:

Write the value and dimensional formula of the Stefan-Boltzmann constant.

The adjoining diagram shows the spectral energy density distribution $E_\lambda$ of a black body at two different temperatures. If the areas under the curves are in the ratio $16 : 1$,the value of temperature $T$ is ......... $K$. (in $,000$)