The absorption coefficient value of a perfect black body is

At a high temperature,a body emits radiation of wavelengths $\lambda_1, \lambda_2, \lambda_3,$ and $\lambda_4$ only. At a lower temperature,which of the following wavelengths will it absorb?

$A$ 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:

According to Kirchhoff's law,the ratio of emissive power to absorptive power for all bodies is:

What would happen if the greenhouse effect were not present?

The intensity of direct sunlight on a surface normal to the rays is $I_0$. What is the intensity of direct sunlight on a surface,whose normal makes an angle of $60^{\circ}$ with the rays of the sun?