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

$A$ rectangular black body of temperature $127^{\circ} C$ has surface area $4 \ cm \times 2 \ cm$ and rate of radiation is $E$. If its temperature is increased by $400^{\circ} C$ and surface area is reduced to half of the initial value,then the rate of radiation is:

The temperatures of two bodies $A$ and $B$ are respectively $727^{\circ}C$ and $327^{\circ}C$. The ratio $H_A:H_B$ of the rates of heat radiated by them is

If the temperature of a black body increases from $7^oC$ to $287^oC$,then the rate of energy radiation increases by a factor of:

$A$ 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 temperature at which a black body of unit area loses its energy at the rate of $1 \text{ J/s}$ is: