Biology
Describe the mechanism of focusing the image of a distant object in your eye when you raise your head after reading a book.
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Answer
Light rays from the object enter the eyes through the transparent structures.
For distant vision, the lens is more flattened or thinner.
For near vision, the lens becomes more convex or rounded.
While reading a book, the lens is more convex or rounded due to contraction of ciliary muscles because the book is usually read from a short distance. When we raise our head and look at a distant object, the ciliary muscles relax to build the tension on the suspensory ligament so that they can stretch the lens. This change in the curvature of the lens makes us focus on distant object.


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Aman's father, aged 50 years, is suffering from an eye defect. He can see the distant objects clearly but not the nearby ones. He keeps the newspaper and books far away from his eyes to read. Answer the following questions :
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The eye is sensitive to light and is responsible for vision. The main parts of an eye are sclera, cornea, retina and lens. Lens passes the light rays to the retina through vitreous humour. Retina is the sensitive layer of the eye which contains sensory cells for image formation. The impulses of the image are then carried from retina to the brain through optic nerves.
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