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Homework Help: About Lenses

  1. Jun 25, 2010 #1
    1. The problem statement, all variables and given/known data

    The moon is observed using a telescope that has an objective lens with a focal length of 3.0 m and an eyepiece with a focal length of 7.5 cm. What is the angular diameter of the moon if the earth-moon distance is 3.85 × 108 m and the diameter of the moon is 3.48 × 106 m?
    (a) 0.36 rad (c) 9.0 rad (e) 40 rad
    (b) 4.7 rad (d) 22 rad


    2. Relevant equations

    0 = ho / do


    3. The attempt at a solution

    0 : the angular size.
    ho: the high of the object
    do: the distance of the object
     
  2. jcsd
  3. Jun 25, 2010 #2

    collinsmark

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    Hello A B C,

    What do you think?
     
  4. Jun 25, 2010 #3
    I think it's 0.36 rad, but I'm not sure
     
  5. Jun 25, 2010 #4

    collinsmark

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    Fair enough. :smile: But if you want us to confirm, you'll have to show us your work. :cool:

    Let me ask you,
    (i) What's the angular diameter of the moon without the telescope?
    (ii) What's the telescope's magnification?
    (iii) Are you more sure of your answer after finding (i) and (ii)? :wink:
     
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