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Homework Help: Find distance beyond the myopic farpoint

  1. Sep 30, 2016 #1
    1. The problem statement, all variables and given/known data
    A myopic person has a far point of 150cm and can see objects clearly at 20cm near point. What is the object distance?

    2. Relevant equations

    Thin lens equation 1/f =1/d1-do.

    3. The attempt at a solution

    di = -150cm because it's on the left of the lens. do = should = infinity, but I needed to know what the actual object distance is...beyond the myopic farpoint. I'm not sure that the 20cm near point is relevant. Does this mean that the actual object distance is do=1/0 and rearrange to find the actual object distance. However I'm not sure how this would work.
  2. jcsd
  3. Sep 30, 2016 #2


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    The first sentence makes sense, but the second one does not. It seems that there is some missing information. The first sententence tells us that this person's eye can forcus on objects within the range 20 cm out to 150 cm. Now all of a sudden the sencond sentence wants to know where the object is located??? I get the impression that the rest of the missing information concerns a problem where this person has glasses on which produces an image of some object located outside this range?
  4. Sep 30, 2016 #3
    Hi there
    This is the question
    "What is the object distance when a myopic person with a far point of 150 cm, can see near images clearly at 20 cm from the eye."

    I keep thinking that I need more information.
  5. Oct 3, 2016 #4


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    The question might mean that the person is wearing glasses to enable her to see distant objects clearly, but now she is looking at an object which results in an image of it being formed 20 cm in front of the eye???
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