Infrared radiation is detected by

The graph shown in the adjacent diagram represents the variation of temperature $(T)$ of two bodies,$x$ and $y$,having the same surface area,with time $(t)$ due to the emission of radiation. Find the correct relation between their emissivities $(e)$ and absorptive powers $(a)$.

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?

Why are the bottom layers of cooking vessels kept black in color?

We consider the radiation emitted by the human body. Which of the following statements is true?

For a perfectly black body,its absorptive power is