Question

Minimum focal length of eye lens of normal person is

• A. 25 cm
• B. 1.5 cm
• C. 25/9 cm
• D. 25/11 cm

Answer 1

The correct option is D 25/11 cm

Minimum focal length is achieved when nearest object is seen by the eye lens. Using lens equation,

$\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$

$\frac{1}{f}=\frac{1}{2.5}-\frac{1}{-25}=\frac{11}{25}$

Hence minimum focal length of normal person is $f=\frac{25}{11}cm$