Why is a normal eye not able to see clearly the objects placed closer than 25 cm?
The normal eye not able to see the objects very clearly that is placed closer than 25 cm because to see the nearest objects within the range before 25 cm, ciliary muscles should be contracted, suspensory ligament should be in the relaxed state, lens should be thick or more convex (increase in the thickness of lens, focal length get short that is adjusted for focusing on the near objects very clearly) and refraction should be increased to see clear image. And, the too much contraction of the ciliary muscles cause stress on the eyes. Thus, the normal eye is unable to see the objects placed closer than 25cm.
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