NTA Abhyas JEE Main2020PhysicsThermal Properties of MatterPractice
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 ). Both of these bodies lose heat only due to the emission of radiation. Find the correct relation between the emissive and absorptive power of the two bodies.
Options
- AE x > E y   and   a x < a y
- BE x < E y   and   a x > a y
- CE x > E y   and   a x > a y
- DE x < E y   and   a x < a y
Correct answer
C. E x > E y   and   a x > a y
Step-by-step solution
Rate of cooling - dT dt ∝ emissivity e From the graph, - dT dt x > - dT dt y ∴ e x > e y Further emissivity ( e ) ∝ absorptive power ( a ) (good absorbers are good emitters also) ∴ a x > a y