What changes take place in the shape of eye-lens : (a) when the eye is focused on a near object?

(b) when the eye is focused on a distant object ?

Fill in the following blanks with suitable words:

(a) Most of the refraction of light rays entering the eye occurs at the outer surface of the _______

(b) The part of eye sensitive to light is_______

(c) The part of eye which alters the size of the pupil is_______

(d) When light is dim, the pupil becomes_______

(e) The iris controls the amount of_______entering the eye.

(f) The ciliary muscles control the shape of the _______

(g) To bring light from a distant object to a focus on the retina of the eye, the convex eye-lens needs to be made_______

(h) To bring light from a near object to a focus on the retina of the eye, the convex eye-lens needs to be made_______

Why is a normal eye not able to see clearly the objects placed closer than 25 cm?

The eyes of a person are focused (i) on a nearby object, and (ii) on a distant object, turn by turn. In which case:

(a) the focal length of eye-lens will be the maximum ?

(b) the converging power of eye-lens will be the maximum?

What change is made in the eye to enable it to focus on objects situated at different distances ? Illustrate your answer with the help of diagrams.