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

$Assertion :$ Bodies radiate heat at all temperatures.
$Reason :$ Rate of radiation of heat is proportional to the fourth power of absolute temperature.

If $A$ represents Boltzmann constant,$B$ represents Planck's constant and $C$ represents speed of light in vacuum,then the quantity having the dimensions of $A^4 B^{-3} C^{-2}$ is

Spheres $P$ and $Q$ are uniformly constructed from the same material,which is a good conductor of heat,and the radius of $Q$ is thrice the radius of $P$. The rate of fall of temperature of $P$ is $x$ times that of $Q$ when both are at the same surface temperature. The value of $x$ is:

$A$ black body emits energy at the rate of $1.0 \times 10^{6} \ J/s \cdot m^{2}$ at $127^{\circ}C$. At what temperature will the energy emission rate be $16.0 \times 10^{6} \ J/s \cdot m^{2}$ in $^{\circ}C$?

The temperature of a piece of iron is $27^{\circ}C$ and it is radiating energy at the rate of $Q \text{ kW m}^{-2}$. If its temperature is raised to $151^{\circ}C$,the rate of radiation of energy will become approximately ....... $Q \text{ kW m}^{-2}$.