$A$ solid sphere at a temperature $T \ K$ is cut into two hemispheres. The ratio of energies radiated by one hemisphere to the whole sphere per second is

The actual temperature of a black body is $727^{\circ}C$. At what temperature in $K$ will the black body emit twice the radiation?

In the $MKS$ system,Stefan's constant is denoted by $\sigma$. In the $CGS$ system,the multiplying factor of $\sigma$ 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 $W$)

At $273^{\circ} C$,the emissive power of a perfectly black body is $R$. Its emissive power at $0^{\circ} C$ is:

If a substance at temperature $T$ is kept in surroundings at temperature $T_S$,what is the net rate of loss of radiation energy?