The graph, shown in the adjacent diagram, represents the variation of temperature (T) of two bodies, x and y having same surface area, with time (t) due to the emission of radiation. Find the correct relation between the emissivity and absorptivity power of the two bodies

Options

A. `E_(x)ltE_(y),a_(x)lta_(y)`
B. `E_(x)gtE_(y),a_(x)lta_(y)`
C. `E_(x)ltE_(y),a_(x)gta_(y)`
D. `E_(x)gtE_(y),a_(x)gta_(y)`

Answer

D

Explanation

From the graph of T against t, we find that the slope of x `gt` slope of y or `((dT)/(dt))_(x)gt((dT)/(dt))_(y)`
The temperature of the body x decrease more rapidly than that of y.
`thereforeE_(x)gtE_(y)` or x is a better emitter.
Similarly from Kirchhoff's law, a good emitter is a good absorber.
`thereforea_(x)gta_(y)`. Thus (d) is the correct choice.