Please show all work/answers legibly. For humans with good eyesight, they should

Question

Please show all work/answers legibly.

For humans with good eyesight, they should be able to focus on objects as close as 25 cm to their eye without difficulty. This is called the "near point". A woman is not able to focus on objects that are closer to her eyes than 550 mm unless she wears eyeglasses. Her glasses enable her to clearly see objects at the near point of an average human (and no closer). It does this by taking an object at the nominal near point and moving the image to where the woman we can see it. (a) Is she myopic or hyperopic? (b) Are her glasses made from converging lenses or diverging lenses? (c) What is the strength of the lenses in her glasses? (Express your answer in diopters.)

Explanation / Answer

a) she is hyperopic.:

As she is unable to focus an object that are closer to eyes than 550 mm ( 55 cm) .

Heperopic is a condition in which strength of cornea and eye lens combination is too weak ,when eye muscles are totally relaxed , so the image of distance object is formed behind the ratina.

Hence she can not focus on objects at conventional near point (25 cm) but can focus distant objects.

b) Her glasses are made from positive lens( convergent) , which strengthen cornea and eye just enough so that resulting focal length when eye muscles are relaxed matches the distance back to ratina

C) strength of lenses measured in diopters ,

Focal length of cornea and eyelens should be about 20 mm

Strength of lens = 1/0.020 = 50 diopters

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