If the ambient temperature is $300 \ K$,the rate of cooling at $600 \ K$ is $H$. In the same surroundings,the rate of cooling at $900 \ K$ is:

$A$ black metal foil is warmed by radiation from a small sphere at temperature $T$ and at a distance $d$. It is found that the power received by the foil is $P$. If both the temperature and distance are doubled,the power received by the foil will be:

Which of the following graphs correctly represents the relation between $\ln E$ and $\ln T$, where $E$ is the amount of radiation emitted per unit time from unit area of a body and $T$ is the absolute temperature?

Star $A$ has radius $r$ and surface temperature $T$,while star $B$ has radius $4r$ and surface temperature $T/2$. The ratio of the power radiated by the two stars,$P_A : P_B$,is:

$A$ spherical black body with a radius of $24\;cm$ radiates $440\;W$ power at $500\;K$. If the radius were halved and the temperature doubled,the power radiated in watt would be

$A$ black rectangular surface of area '$A$' emits energy '$E$' per second at $27^{\circ}C$. If length and breadth are reduced to $(1/3)^{rd}$ of their initial values and temperature is raised to $327^{\circ}C$,then the energy emitted per second becomes: