Question

The far point of a normal eye is :

• A. 25 cm
• B. infinity
• C. 15 cm
• D. 35 cm

Hint:

For a normal human eye, remember these two key points:
{Near Point (Closest clear vision):} Approximately 25 cm.
{Far Point (Farthest clear vision):} Infinity (\(\infty\)). If someone's far point is less than infinity, they are myopic (short-sighted).

Answer 1

The Correct Option is B

Concept: The human eye has a range of distances over which it can focus clearly. This range is defined by the near point and the far point. Step 1: Defining Far Point The far point of the eye is the maximum distance at which an object can be seen clearly without any strain on the eye. For the eye to see a distant object, the ciliary muscles are relaxed, and the eye lens is at its thinnest (longest focal length). Step 2: Far Point for a Normal Eye For a person with normal vision (emmetropic eye), the eye is able to focus parallel rays of light (coming from infinitely distant objects) precisely onto the retina when the eye is in its relaxed state. Therefore, the far point of a normal human eye is considered to be at infinity (\(\infty\)). This means a person with normal vision can see very distant objects, like stars or mountains, clearly. Step 3: Understanding other options
(1) 25 cm: This is the conventional {near point} (least distance of distinct vision) for a normal young adult eye, not the far point. It's the closest distance at which objects can be seen clearly.
(3) 15 cm and (4) 35 cm: These are specific finite distances and do not represent the far point of a normal eye. If the far point were a finite distance like these, it would indicate myopia (short-sightedness). Thus, the far point of a normal eye is at infinity.