If the eye is kept very close to a coverging lens (focal length `= 10 cm`) and at the optical centre of the lens and an object is kept at distance 'd' of the object from the lebs so that its image can be seen clearly by the defect free eye is :
.

Options

A. 10 cm
B. 25 cm
C. `50//3` cm
D. `50//7` cm

Answer

A

Explanation

`Rightarrow1/(f_(eq))=1/v-1/u=1/2.5-1/(-x)`
`x_(max)Rightarrowf_(eq)=max. Rightarroweye is focussed at infty`
`1/(f_(eq))+1/(f_(l e ns))=1/(2.5)+1/x`
`=10cm Rightarrow x=10` cm]