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Q85 (NDA-II/2023) Science & Technology › Basic Science (Physics, Chemistry, Biology) Official Key

Ramesh cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power

Explanation

Ramesh is suffering from Myopia (nearsightedness), a defect where a person can see nearby objects clearly but cannot see distant objects distinctly. In this case, his far point is 2 m instead of infinity.

To correct Myopia, a concave (diverging) lens is used. The lens must form a virtual image of a distant object (at infinity) at the person's actual far point. Using the lens formula:

  • Object distance (u) = ∞
  • Image distance (v) = -2 m (far point)
  • Lens Formula: 1/f = 1/v - 1/u
  • 1/f = 1/(-2) - 1/∞ = -1/2 = -0.5 m⁻¹

The Power (P) of a lens is defined as the reciprocal of its focal length in meters (P = 1/f). Therefore, P = -0.5 D. The negative sign indicates that the lens is concave, which is consistent with the treatment for Myopia.

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SIMILAR QUESTIONS

CDS-I · 2010 · Q112 Relevance score: -0.96

Consider the following statements 1. A person with myopia can see distant objects distinctly but cannot see nearby objects clearly. 2. A person with hypermetropia cannot see distant objects clearly. 3. A person with presbyopia can see nearby objects without corrective glasses. Which of the statements given above is/are not correct ?

NDA-II · 2025 · Q73 Relevance score: -1.91

A person can see nearby objects clearly but cannot see distant object distinctly, the person is suffering with

NDA-I · 2012 · Q86 Relevance score: -2.03

Consider the following statements : Hypermetropia is a defect of vision in which 1. a person cannot see the distant objects clearly 2. a person cannot see the near objects clearly 3. the near point of the eye gets shifted away from the normal position 4. the far point of the eye gets shifted towards the eye Which of the statements given above are correct?

CAPF · 2025 · Q111 Relevance score: -2.57

Which one among the following statements related to human eye is correct? (a) For a person suffering from short-sight defect, the image of a distant object is focused behind the retina. (b) Short-sight defect can be corrected by a converging spectacle lens. (c) For a person suffering from long-sight defect, the image of a near object is focused behind the retina. (d) Long-sight defect can be corrected by a diverging spectacle lens.