Let consider the human eye to be composed of a thin lens having uniform index of refraction n = 1.39, having fluid of n = 1 within, with the light-receptive cells a distance 21.8 mm from the lens. The eye can ‘focus’ on different distances by varying the radius of curvature of its lens.
Determine the radius of curvature for this lens if you are looking at an object a distance of 56.5 mm from your eye's lens. (All incident light rays should still strike the light-receptive cells at the similar distance as before)