The surface of a household radiator has an emissivity of `0.55` and an area of `1.5 m^(2)`.
(a) At what rate is radiation emitted by the radiator when its temperature is `50^(@)C`?
(b) At what rate is the radiation absorbed by the radiator when the walls of the room are at `22^(@)C`? (c ) What is the net rate of radiation from the radiator? (stefan constant `sigma = 6 xx 10^(-8)W//m^(2)-K^(4))`

Answer

`539 W, 375W, 164 W`

Explanation

(a) `e sigma AT^(4) = 0.55 xx 6 xx 10^(-8) xx 1.5 xx (323)^(4) = 539W`
(b) `e sigma AT_(surr)^(4) = 0.55 xx 6 xx 10^(-8) xx 15 xx (295)^(4) = 375W`
(c ) `539 -375 = 164 W`.