The diameter of the sun is `1.4 X 10^9m` and its distance from the earth is `1.5 X 10^11 m`. Find the radius of the image of the sun formed by a lens of focal length 20 cm.

Answer

C

Explanation

Here `u=-150x10^1cm`
f=20cm
Using lens formula
`1/v-1/u=1/f`
`rarr 1/v=1/20-1/(150x10^11)`
`=(750x10^9-1)/(150xx10^11)`
`=~=(750xx10^9)/(150x10^11)`
`rarr v=(150xx10^11)/(750xx10^9)`
`We know magnification
`(m)=v/u=h_2/h_1`
`rarr h_2-=v/uxxh_1`
`=(150xx10^110/(750xx10^9xx150xx10^11)xx0.7xx10^11mm`
`=0.93mm`