Thermal radiation travels at the speed of . . . . . . .

Why is the Sun considered a perfect black body?

$A$ body,which emits radiations of all possible wavelengths,is known as ...........

Three objects colored black,gray,and white can withstand hostile conditions up to $2800\,^oC$. These objects are thrown into a furnace where each of them attains a temperature of $2000\,^oC$. Which object will glow brightest?

Good absorbers of heat are

Heat travels through vacuum by