A solide sphere and a hollow sphere of the same material and of equal radii are heated to the same temperature
(i) Both will emit equal amount of radiation per unit time in the beginning
(ii) Both will absorb equal amount of radiation from the surrounding in the beginning
(iii) The initial rate of cooling `dT//dt` will be same for the two spheres
(iv) The two spheres will have equal temperatures at any instant

Options

A. (i),(ii)
B. (ii),(iii)
C. (iii).(iv)
D. (i),(ii)

Answer

A

Explanation

(1) `u = e sigma A T^(4), u_(0) = e sigma A T_(0)^(4)`
`(dT)/(dt) = (e sigma A)/(ms) (T^(4) - T_(0)^(4))`
`((dT)/(dt)) prop (1)/(m)`
The masses of spheres will be different (iii) and (iv) are wrong