Question

For a healthy human eye, the near point and far point are respectively

• A. 0 and infinity
• B. 25 cm and 250 cm
• C. 25 cm and infinity
• D. 0 and 25 cm

Hint:

Remember these standard values: Near Point = 25 cm, Far Point = Infinity. Defects of vision like myopia (nearsightedness) and hypermetropia (farsightedness) occur when these points shift from their normal positions.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The question asks for the standard values of the near point and far point for a normal, healthy human eye.
\[\begin{array}{rl} \bullet & \text{Near Point: The closest distance at which an object can be seen clearly without any strain on the eye. This is also known as the least distance of distinct vision. } \\ \bullet & \text{Far Point: The farthest distance at which an object can be seen clearly. } \\ \end{array}\]

Step 2: Detailed Explanation:
For a young adult with normal vision (emmetropia):
\[\begin{array}{rl} \bullet & \text{The eye can focus on objects as close as approximately 25 cm. If an object is brought closer than this, the image becomes blurry. So, the near point is 25 cm. } \\ \bullet & \text{The eye can see objects at a very large distance, theoretically up to infinity, without any strain. This is because when viewing a distant object, the ciliary muscles are relaxed, and the eye lens has its maximum focal length. So, the far point is infinity. } \\ \end{array}\]

Step 3: Final Answer:
The near point for a healthy human eye is 25 cm, and the far point is infinity.