Parallel rays of light of intensity `I=912 WM^-2` are incident on a spherical black body kept in surroundings of temperature 300K. Take Stefan-Boltzmann constant `sigma=5.7xx10^-8` `Wm^-2K^-4` and assume that the energy exchange with the surroundings is only through radiation. The final steady state temperature of the black body is close toA. `330K`B. `660K`C. `990K`D. `1550K`

Parallel rays of light of intensity `I=912 WM^-2` are incident on a sp

1.	Parallel rays of light of intensity `I=912 WM^-2` are incident on a spherical black body kept in surroundings of temperature 300K. Take Stefan-Boltzmann constant `sigma=5.7xx10^-8` `Wm^-2K^-4` and assume that the energy exchange with the surroundings is only through radiation. The final steady state temperature of the black body is close toA. `330K`B. `660K`C. `990K`D. `1550K`
Answer» Correct Answer - A (a) In steady state `Energy lost =Energy gained` `sigma(T^4-T_0^4)xx4piR^2=I(piR^2)` `:. 5.7xx10^-8[T^4-(300)^4]xx4=912` `:. T=330K`

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