For two identical cylindrical emitters,the ratio of their radii is $1:4$ and the ratio of their temperatures is $2:1$. The ratio of the amount of heat emitted by them is ....... (Assume length is proportional to radius for the cylinders).

The rate of radiation of a black body at $0^{\circ}C$ is $E \ J/s$. The rate of radiation of this black body at $273^{\circ}C$ will be:

$A$ black body is at temperature $827^{\circ}\text{C}$. The rate at which it emits energy is proportional to

$A$ solid cylinder of radius $r_1=2.5 \ cm$, length $l_1=5.0 \ cm$ and temperature $40^{\circ}C$ is suspended in an environment of temperature $60^{\circ}C$. The thermal radiation transfer rate for the cylinder is $1.0 \ W$. If the cylinder is stretched until its radius becomes $r_2=0.50 \ cm$, the thermal radiation transfer rate is changed to (in $W$)

$A$ black body is at $727^\circ C$. It emits energy at a rate which is proportional to

$A$ tungsten body of diameter $2.3 \ cm$ is at $2000 \ ^oC$. It radiates $30 \%$ of the energy radiated by a black body of the same radius and temperature. Find the radius of a black body which will radiate energy at the same rate at the same temperature (in $cm$).