$A$ perfectly black body emits radiation at a temperature $T_1 \ K$. If it is to radiate at $16$ times this power,its temperature $T_2 \ K$ should be: (in $T_1$)

The temperature of a body is $400^{\circ}C$. Assume the temperature of the surroundings is negligible. At what temperature will the body emit double the energy?

$A$ black sphere has radius $R$ whose rate of radiation is $E$ at temperature $T$. If the radius is made $R/3$ and the temperature $3T$,the rate of radiation will be:

$A$ black body of surface area $10 \ cm^2$ is heated to $127^{\circ}C$ and is suspended in a room at temperature $27^{\circ}C$. The initial rate of loss of heat from the body at the room temperature will be ...... $W$.

Two spheres $P$ and $Q$ have the same emissivity and radii $8 \ cm$ and $2 \ cm$ respectively. They are maintained at temperatures $127^{\circ}C$ and $527^{\circ}C$ respectively. Find the ratio of the radiant energy emitted by $P$ to that by $Q$.

Two spherical black bodies of radius $r_{1}$ and $r_{2}$ with surface temperatures $T_{1}$ and $T_{2}$ respectively,radiate the same power. Then the ratio $r_{1}: r_{2}$ is: