Question
Ellen wears eyeglasses with the prescription $-1.0 \mathrm{D}$.a. What eye condition does Ellen have?b. What is her far point without the glasses?
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Ellen has a prescription of $-1.0 \mathrm{D}$, which indicates that she is nearsighted (myopic). Show more…
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Kelly normally wears glasses with a prescription of +2 D to see her computer screen from a comfortable distance of 40 cm, but they've gone missing. At the pharmacy, she could only find a replacement pair of reading glasses with a prescription of +1.8 D. a) Is Kelly farsighted or nearsighted, and how can you tell? b) Will Kelly have to move her screen closer or farther to see it clearly with the weaker lenses and why? c) Based on Kelly's normal prescription, where is her natural near point without corrective lenses? (*Hint: Draw a sketch!) d) How far must Kelly sit from her screen in order to see it clearly when wearing the weaker glasses? (*Hint: Draw a new sketch!)
Eleanor is nearsighted and has begun to lose accommodation as she gets older, so she wears bifocals with prescriptions of -1.75 D and +1.5 D. (Bifocals are eyeglasses that have small lenses for reading embedded within big ones to see distant objects; they are like having two pairs of glasses in one!) What are Eleanor's near point and far point when she isn't wearing glasses? (*Hint: Treat this like two separate problems. Tackle the nearsightedness and the farsightedness separately.)
4) Eleanor is nearsighted and has begun to lose accommodation as she gets older, so she wears bifocals with prescriptions of -1.75 D and +1.5 D. (Bifocals are eyeglasses that have small lenses for reading embedded within big ones to see distant objects; they are like having two pairs of glasses in one!) What are Eleanor's near point and far point when she isn't wearing glasses? (*Hint: Treat this like two separate problems. Tackle the nearsightedness and the farsightedness separately.)
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