Presbyopia is the tendency to gradually become far-sighted (hyperopic) as you age. If you have normal vision when you are young, you have a near point of 25 cm.
Presbyopia is the tendency to gradually become far-sighted (hyperopic) as you age. If you have normal vision when you are young, you have a near point of 25 cm.
A. If the distance between your eye's lens and retina is 1.67 cm, what is the focal length of your eye's lens when you look at an object at your near point?
f = _______ cm
B. As you get older, suppose that the near point of your eye increases to 48 cm. What is the focal length of your eye's lens when you look at an object at your near point now?
f = ________ cm
C. With your near point at 48 cm, what is the focal length of the corrective lens (placed directly in front of your eye's lens) which you would need to look at an object that is 25 cm in front of your eye?
f = ________ cm
D. As you continue to age, the corrective lenses will no longer be sufficient to allow you to see an object that is 25 cm in front of your eye. When you are wearing your corrective lenses, suppose that you can now see objects only if they are no closer than 42 cm in front of your eye. What is the actual near point of your eye now?
N = _______ cm
What is the focal length of your eye's lens that corresponds to this new near point?
f = ______ cm
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