Q. For a normal eye, the cornea of eye provides a converging power of 40 D and the least converging power of the eye lens behind the cornea is 20 D. Using this information, the distance between the retina and the cornea-eye lens can be estimated to be
A) 5 cm
B) 2.5 cm
C) 1.67 cm
D) 1.5 cm
Explanation
[Solution from source] For a relaxed normal eye viewing a distant object, the total power 40 + 20 = 60 D must focus the image on the retina. f = 1/60 m = 100/60 cm ≈ 1.67 cm, which is the cornea–retina distance. Using only the cornea power (40 D) gives 2.5 cm. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.