Question

The minimum focal length of the eye-lens of a healthy human being is

• A. 2.7 cm
• B. 2·5 cm
• C. 25 cm
• D. 1 cm

Answer 1

The Correct Option is C

The focal length of the eye-lens varies depending on the object’s distance due to the process called accommodation.

In a healthy human eye, when viewing the nearest object clearly (at the near point), the focal length is the minimum.

The near point for a healthy human being is about 25 cm, but the lens itself changes shape to focus that close.

In such a condition, the focal length of the eye-lens becomes approximately:

$f \approx 2.5 \, \text{cm}$

This is the minimum focal length the eye-lens can attain when fully accommodating.

Final Answer: 2·5 cm