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Homework Help: Studying for exam- telescope problem (help )

  1. Jan 13, 2010 #1
    studying for exam- telescope problem (help!!)

    1. The problem statement, all variables and given/known data

    What diameter optical telescope on the Earth would you need to resolve a lunar lander 3 m across on the surface of the moon 3.8e8m away?

    2. Relevant equations



    3. The attempt at a solution
    the only thing I can think of is to use theta=1.22lamda/d.... but what do I do with it? help!
     
  2. jcsd
  3. Jan 13, 2010 #2
    Re: studying for exam- telescope problem (help!!)

    You need to assume a typical value for lambda. A wavelength in the visible spectrum.
    d is the diameter you need to calculate.
    theta is the angular separation of two points that can just be resolved.
    What is the angular separation of those two points on the moon?
     
  4. Jan 13, 2010 #3
    Re: studying for exam- telescope problem (help!!)

    oh! that makes sense. so is the angular separation the size of the lander divided by the distance to it?
     
  5. Jan 13, 2010 #4
    Re: studying for exam- telescope problem (help!!)

    That should work fine.

    (Welcome to Physics Forums, by the way)
     
  6. Jan 13, 2010 #5
    Re: studying for exam- telescope problem (help!!)

    yay!! thank you!!
     
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