When the human eye is focused on an object,the ciliary muscles are least strained when the object is at:

$A$ person can see objects clearly only when they lie between $50\, cm$ and $400\, cm$ from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens the person has to use will be

The near point and far point of a person are $40\,cm$ and $250\,cm$ respectively. Determine the power of the lens he/she should use while reading a book kept at a distance of $25\,cm$ from the eye $..........D$

$A$ person wears glasses of power $-2.0 \, D$. The defect of the eye and the far point of the person without the glasses will be

$A$ person cannot see an object clearly if it is placed beyond $100 \, cm$. Find the power of the lens required to see an object clearly at infinity.

When the human eye is focused on an object,at what position are the ciliary muscles least strained?