For a normal eye, the cornea of eye provides a converging power of `40 D` and the least converging power of the eye lens behind the cornea is `20 D`. Using this information, the distance between the retina and the cornea eye lens can be estimated to be

Options

A. `2.5 cm`
B. `1.67 m`
C. `1.5 cm`
D. `5 cm`

Answer

B

Explanation

The system of cornea and eye - lens should form the image of the distant object at retina.
Total converging power of eye `=40D+20D`
`=60D`
Using Lens formula
`(1)/(v)-(1)/(oo)=(60)/(100)`
`v=(5)/(3)cm=1.67cm`
Thus, the distance between cornea and retina should be 1.67 cm.