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