The minimum power of the eye lens is 40 D. If the far point of the normal eye is infinity. Find the size of the eye ball.
Power of eye lens = P
P = 40 D
Focal length = f
f = 
f = 
= 0.025 m
= 2.5 cm
Radius of curvature = 2f
= 5 cm
The eye ball has the radius of 5 cm
19