A boy is trying to start a fire by focusing sunlight on a piece of paper using an equiconvex lens of focal length `10cm`. The diameter of the sun is `1.39xx10^(9)m` and its mean distance from the earth is `1.5xx10^(11)m`. What is the diameter of the sun's image on the paper ?

Options

A. `9.2 xx 10^-4 m`
B. `6.5 xx 10^-4 m`
C. `6.5 xx 10^-5 m`
D. `12.4 xx 10^-4 m`

Answer

A

Explanation

`("Diameter of sun's image")/("Distance of sun")`
=`("Distance of image from lens")/("Distance of sun from lens")`
`(x)/(1.39 xx 10^9) = (10^-1)/(1.5 xx 10^11) = 9.2 xx 10^-4 m`.