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

Answer

A

Explanation

From the relation
`I/O=v/u`
Here, `O=1.39xx10^(9), v=0.1 m`
`u=1.5xx10^(11) m`
`:. I=0.1/(1.5xx11^(11)) xx1.39xx10^(9)`
`=9.2xx10^(-4)m`