The earth receives at its surface radiation from the sun at the rate of `1400 Wm^-2.` The distance of the centre of the sun from the surface of the earth is `1.5xx10^11 m` and the radius of the sun is `7xx10^8m.` Treating the sun as a black body, it follows from the above data taht its surface temperature is ......K

Answer

C

Explanation

The energy received per second per unit area from Sun at a
distance of `1.5xx10^11m is 1400J//sm^2.` The total energy
released by Sun//per second.
`=1400xx4pixx(1.5xx10^11)^2.` ltbRgt `:. The total energy released per second per unit surface
area of the sun
`=(1400xx4pixx(2.5xx^11)^2)/(4pixx(7xx10^8)^2)`
This energy E is also equal to `E=sigmaT^4`
`:. T=[(1400xx4pixx(1.5xx10^11)^2)/(4pixx(7xx10^8)^2xx5.67xx10^-8)]^(1/4)~~5803K`