Consider the human eye to be composed of a thin, plano-convex, lens (similar to
ID: 1453729 • Letter: C
Question
Consider the human eye to be composed of a thin, plano-convex, lens (similar to the one shown in your lab write up and in earlier problems of this pre-lab) of uniform index of refraction n = 1.45, submerged into fluid of n = 1, with the light-receptive cells a distance 20.1 mm from the lens. The eye can "focus" on different distances by changing the radius of curvature of its lens.
Find the radius of curvature for this lens when you are looking at very distant objects. (all incident light rays must hit the light-receptive cells at the same point)
Find the radius of curvature for this lens when you are looking at an object a distance of 64 mm from your eye's lens. (all incident light rays must still hit the light-receptive cells at the same distance as before)
Explanation / Answer
image distance s' = 20.1 mm
object distance s = infinity
from lens equation
1/s + 1/s' = 1/f
1/infinity + 1/s' = 1/f
f = s' = 20.1 mm
from lens makers equation
(n1/n2 - 1)*(1/R1 - 1/R2 ) = 1/f
(1.45/1 - 1)*(1/R + 1/R) = 1/20.1
Radius of curvature R = 18.09 mm <<<----------answer
++++++++++
object distance s = 64 mm
image distance s' = 20.1 mm
(n1/n2 - 1)*(1/R1 - 1/R2 ) = 1/s + 1/s'
(1.45/1 - 1)*(1/R + 1/R) = 1/64 + 1/20.1
R = 13.77 mm <<<<<--answer