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. `12.4 x 10^(-4)` m
B. ` 9.2 x 10^(-4)` m
C. `6.5xx10^(-4)` m
D. `6.5xx1O^(-5)` m

Answer

2

Explanation

`1/v - 1/u = 1/f`
`1/v = 1/u + 1/f`
`u/v = u/f + 1`
`v/u = (f/(f+u))= d_(image)/d_(sum)`
`10^(-1)/(1.5xx10^(11))=d_(image)/(1.39xx10^(9))`
`9.2xx10^(-4) = d_(image)`