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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
1.5 cm
B
5 cm
C
2.5 cm
D
1.67 cm
Detailed Solution
For a normal eye, rays from infinity focus on the retina with the lens at its minimum power.
Combined power = 40 D + 20 D = 60 D
The distance between the retina and the cornea-eye lens equals the focal length: $f = \frac{1}{60}$ m = 1.67 cm
Combined power = 40 D + 20 D = 60 D
The distance between the retina and the cornea-eye lens equals the focal length: $f = \frac{1}{60}$ m = 1.67 cm