Two electric lamps $A$ and $B$ radiate the same power. Their filaments have the same dimensions and have emissivities $e_A$ and $e_B$. Their surface temperatures are $T_A$ and $T_B$. The ratio $\frac{T_A}{T_B}$ will be equal to :-

$A$ black body of mass $34.38 \ g$ and surface area $19.2 \ cm^2$ is at an initial temperature of $400 \ K$. It is allowed to cool inside an evacuated enclosure kept at a constant temperature of $300 \ K$. The rate of cooling is $0.04 \ ^{\circ}C/s$. The specific heat of the body in $J \ kg^{-1} \ K^{-1}$ is (Stefan's constant $\sigma = 5.73 \times 10^{-8} \ W \ m^{-2} \ K^{-4}$)

$A$ 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 $^{\circ}C$?

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

The radiated power of a body at $400 \,K$ is $1000 \,W$. If the temperature is raised to $800 \,K$, what would be the radiated power of the body (in $W$)?

The amount of heat energy radiated by a metal at temperature $T$ is $E$. When the temperature is increased to $3T$,the energy radiated is: (in $E$)