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Q25 (NDA-II/2022) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Human anatomy physiology

Human eye can see objects at different distances with contrasting illuminations. This is due to

Result
Your answer: —  Â·  Correct: D
Explanation

The ability of the human eye to see objects at varying distances is primarily due to the mechanism of accommodation [1]. This process involves the adjustment of the eye's focal length by changing the curvature of the crystalline lens [1][2]. The ciliary muscles play a critical role; when they relax, the lens becomes thin, increasing the focal length for distant vision [2]. Conversely, when focusing on nearby objects, the ciliary muscles contract, making the lens thicker and decreasing the focal length [2]. Additionally, the eye manages contrasting illuminations through the iris and pupil, which regulate the amount of light entering the eye [4][5]. While myopia (near-sightedness) and hypermetropia (far-sightedness) are refractive defects that impair this ability, accommodation is the natural physiological function that enables clear vision across a range of distances [1][3].

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > What you have learnt > p. 170
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.1.1 Power of Accommodation > p. 162
  3. [4] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > 10.1 THE HUMAN EYE > p. 161
  4. [5] https://pmc.ncbi.nlm.nih.gov/articles/PMC6634360/
  5. [3] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > Figure 10.3 > p. 164
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