An imaginary line joining the optical centre of the eye lens and the yellow point is called as

For a normal eye,the cornea of the 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 ......... $cm$.

The image formed on the retina is:

$A$ person cannot see objects beyond $3 \, m$. What should be the focal length of the lens required to see objects at $12 \, m$?

If you are using eyeglasses of power $2 D$, what is your near point (in $cm$)?

When objects at different distances are seen by the eye,which of the following remains constant?