At a certain temperature for a given wavelength,the ratio of the emissive power of a body to the emissive power of a black body in the same circumstances is known as:

The velocity of heat radiation in vacuum is

The following figure shows two air-filled bulbs connected by a $U$-tube partly filled with alcohol. One bulb is painted black and the other is painted white (or silver/shiny). What happens to the levels of alcohol in the limbs $X$ and $Y$ when an electric bulb placed midway between the two bulbs is lighted?

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?

Good absorbers of heat are

If Earth did not have an atmosphere,the temperature would be . . . . . . .