The total radiative power emitted by a spherical black body with radius $R$ and temperature $T$ is $P$. If the radius is doubled and the temperature is halved,then the radiative power will be

Assuming the sun to have a spherical outer surface of radius $r$,radiating like a black body at temperature $t^{\circ} C$,the power received by a unit surface (normal to the incident rays) at a distance $R$ from the centre of the sun is,where $\sigma$ is the Stefan's constant.

If the temperature of a body is increased from $-73^{\circ}C$ to $327^{\circ}C$,the ratio of its emissive power will be ...

Two bodies $A$ and $B$ have emissivities of $0.01$ and $0.81$ respectively. The outer surface areas of both bodies are the same. Both bodies emit total radiant power at the same rate. The wavelength $\lambda_B$ corresponding to the maximum spectral radiance for body $B$ is $1.0 \mu m$. If the temperature of body $A$ is $5802 \ K$,then the temperature of body $B$ is .... $K$.

$A$ black body radiates maximum energy at wavelength $\lambda$ and its emissive power is $E$. Now,due to a change in temperature of that body,it radiates maximum energy at wavelength $\frac{\lambda}{3}$. At that new temperature,the emissive power is: (in $E$)

At $273^{\circ} C$,the emissive power of a perfectly black body is $R$. Its emissive power at $0^{\circ} C$ is: