If the temperature of a black body increases from $7^{\circ}C$ to $287^{\circ}C$,then what is the ratio of the rate of energy emission?

$A$ tungsten body of diameter $2.3 \ cm$ is at $2000 \ ^oC$. It radiates $30 \%$ of the energy radiated by a black body of the same radius and temperature. Find the radius of a black body which will radiate energy at the same rate at the same temperature (in $cm$).

The temperature of a body is increased from $T_1 = 127^{\circ}C$ to $T_2 = 227^{\circ}C$. The ambient temperature is $T_0 = 27^{\circ}C$. The energies emitted per second by the body at $T_1$ and $T_2$ are $E_1$ and $E_2$ respectively. The ratio of $\frac{E_2}{E_1}$ is:

$A$ black body radiates energy at a rate of $E \, W/m^2$ at a temperature of $T \, K$. When the temperature is reduced to $T/2 \, K$,the radiated energy will be .....

$A$ very small hole in an electric furnace is used for heating metals. The hole nearly acts as a black body. The area of the hole is $200 \ mm^2$. To keep a metal at $727^{\circ} C$,the heat energy flowing through this hole per second,in joules,is (given $\sigma = 5.67 \times 10^{-8} \ W m^{-2} K^{-4}$):

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