Q.4 (i) (a) Draw a neat labelled diagram of human eye.(b) What is the minimum distance of distinct vision for a normal human eye ?(c) Name the capacity of the eye lens to change its focal length as per need.(d) Name the defect of eye vision in which…

Answer: (b) 25 cm; (c) power of accommodation; (d) presbyopia.

(a) Diagram: draw the eyeball and label the cornea, iris, pupil, aqueous humour, eye lens, ciliary muscles, vitreous humour, retina, blind spot and optic nerve.

(b) The minimum distance of distinct vision for a normal eye is 25 cm.

(c) The ability of the eye lens to change its focal length as needed, using the ciliary muscles, is called the power of accommodation.

(d) Presbyopia: with age the ciliary muscles weaken and the lens loses flexibility, so near objects cannot be seen clearly. It is corrected with a convex lens (or bifocal lenses).