Question 17: How are we able to see nearby and also the distant objects clearly?
Answer:
We can see the near and the distant objects very clearly by the correct actions of ciliary muscles, suspensory ligaments, using the correct lens and by the correct amount of refraction index.
Near objects: When the light rays strike the eyes from the near object rays get diverged. Then greater refraction of light is required to see the near objects. To increase the refraction index, convexity of lens is increased by decreasing the tension in suspensory ligament. Loosening of suspensory ligament allows the lens to shorten by its own elasticity and then the lens becomes thicker and more convex. Thus increase in the thickness of the lens, shorten its focal length which adjusts it to focus on the near objects.
Distant objects: Reverse process occurs to see the distant objects. When we focus on the distant objects, then the eyes are said to be at rest. When the light rays strike on the eyes from distant objects, rays are parallel. At this, the ciliary muscles are fully relaxed, the suspensory ligament is under maximum tension and the lens becomes flattened.
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