Question

The range of vision of a normal human eye is from :

• A. \(100\text{m to } 25\text{cm}\)
• B. \(\text{infinity to } 25\text{m}\)
• C. \(1\text{km to } 25\text{cm}\)
• D. \(\text{infinity to } 25\text{cm}\)

Hint:

For a normal human eye:
Closest clear vision (Near Point) = \(25 \text{ cm}\)
Farthest clear vision (Far Point) = Infinity (\(\infty\)) The range of vision spans all distances between these two points.

Answer 1

The Correct Option is D

Concept: The range of vision describes the span of distances over which a normal human eye can see objects clearly. It is defined by two points: the near point and the far point. Step 1: Define Near Point and Far Point
Near Point (Least Distance of Distinct Vision - LDDV): This is the closest distance an object can be to the eye and still be seen clearly and without strain. For a young adult with normal vision, this is about \(25 \text{ cm}\).
Far Point: This is the farthest distance an object can be from the eye and still be seen clearly. For a normal eye, the far point is at infinity (\(\infty\)). This means we can see very distant objects like stars. Step 2: Determine the Range of Vision The range of vision for a normal eye is from its near point to its far point. So, this range is from \(25 \text{ cm}\) to infinity. Step 3: Match with the given options The options provided list the far point first, then the near point.
Option (1) \(100\text{m to } 25\text{cm}\): Incorrect far point.
Option (2) \(\text{infinity to } 25\text{m}\): Incorrect near point unit (should be cm).
Option (3) \(1\text{km to } 25\text{cm}\): Incorrect far point.
Option (4) \(\text{infinity to } 25\text{cm}\): Correctly states the far point (infinity) and the near point (\(25 \text{ cm}\)). Thus, the range of vision is from \(25 \text{ cm}\) to infinity.