another lens problem from my tutor

ssiding

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Aug 20, 2008
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  1. Pre-Medical
    Optometrists use a linear scale of lens power, measured in diopters, to prescribe corrective lenses. Lens power is given by the equation P = 1/f, where f is the lens focal length in meters. Sufferers of myopia, or nearsightedness, have dificult resolving distant objects because the lenses in their eyes are too strong. If a myopic person has a prescription of -5 diopters, what image do her corrective lenses create for distant objects?

    A. an upright, real image about 20cm in front of her eyes
    B. an uprght, virtual image about 20cm in front of her eyes
    C. an inverted, real image about 20cm behind her eyes
    D. an inverted, virtual image 5 m behind her eyes
     

    soby10

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    Apr 27, 2008
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    1. Pre-Medical
      Myopia or nearsightedness =diverging lenses, farsightedness or hyperopia=converging lenses. Diverg. lenses always make negative virtual upright images, like convex mirrors. Only virtual upright image is answer B. I don't think calculations needed just def. of lenses.
       
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