CBSE Class 10 Science 2017 · Paper 531 · Question 4

Sumit is suffering from myopia (near-sightedness). He can see nearby objects clearly but cannot see distant objects, such as the writing on the blackboard from the back of the classroom, distinctly: his far point is nearer than infinity, and the image of a distant object is formed in front of the retina (ray diagram (b)). It is corrected by a concave (diverging) lens of suitable power, whose focal length is equal in magnitude to the distance of the far point from the lens. The lens makes the parallel rays from a distant object diverge as if they came from the far point O, and the eye lens then forms the image on the retina (ray diagram (c)).