$A$ black body is at a temperature of $500 \; K$. It emits energy at a rate which is proportional to:

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:

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 $Q$.

$A$ black body radiates at the rate of $W$ watts at a temperature $T$. If the temperature of the body is reduced to $T/3$,it will radiate at the rate of (in Watts):

The radiant energy from the sun incident normally at the surface of the earth is $20 \, kcal/(m^2 \cdot min)$. What would have been the radiant energy incident normally on the earth,if the sun had a temperature twice of the present one? (in $kcal/(m^2 \cdot min)$)

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