When $p$ calories of heat is given to a body,it absorbs $q$ calories; then the absorption power of the body will be

The black lines in the solar spectrum during a solar eclipse can be explained by

Why is the Sun considered a perfect black body?

$A$ certain substance emits only the wavelengths ${\lambda _1}, {\lambda _2}, {\lambda _3}$ and ${\lambda _4}$ when it is at a high temperature. When this substance is at a colder temperature,it will absorb only the following wavelengths:

$A$ total radiation of $400 \ J$ is incident on a body. If $20\%$ of the radiation is reflected and $120 \ J$ is absorbed,find the percentage of the transmittive power.

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