The radiation emitted by a star `A` is `1000` times that of the sun. If the surface temperature of the sun and star `A` are `6000 K` and `2000 K` respectively. The ratio of the radii of the star `A` and the sun is:

Options

A. `300 : 1`
B. `600 : 1`
C. `900 : 1`
D. `1200 : 1`

Answer

C

Explanation

`(Q_(1))/Q_(2)=(F_(1)A_(1))/(E_(2)A_(2))=((2000)/(6000))^(4)(A_(1))/(A_(2))or,(A_(1))/(A_(2))=10000xx(3)^(4)`
`(r_(1))/(r_(2))=sqrt((10)^(4)(3)^(4))=100xx9=900:1`