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    Default PHYSICS****Find the focal length of the telescope's objective lens.?



    Mars subtends an angle of 8.0 10-5 rad at the unaided eye. An astronomical telescope has an eyepiece with a focal length of 0.037 m. When Mars is viewed using this telescope, it subtends an angle of 3.10 10-3 rad. Find the focal length of the telescope's objective lens.
    ______m

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    ~1433.75 mm

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    Quote Originally Posted by traxxas View Post
    Mars subtends an angle of 8.0 10-5 rad at the unaided eye. An astronomical telescope has an eyepiece with a focal length of 0.037 m. When Mars is viewed using this telescope, it subtends an angle of 3.10 10-3 rad. Find the focal length of the telescope's objective lens.
    ______m
    Homework ?
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    Thats given me a headache just looking at it. (I said I was a bear of little brains)
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    Quote Originally Posted by davred View Post
    Thats given me a headache just looking at it. (I said I was a bear of little brains)
    LOL. I agree! I was trying to read it and went "huh, are you kidding me!" Makes me feel kinda stupid
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    Quote Originally Posted by traxxas View Post
    Mars subtends an angle of 8.0 10-5 rad at the unaided eye. An astronomical telescope has an eyepiece with a focal length of 0.037 m. When Mars is viewed using this telescope, it subtends an angle of 3.10 10-3 rad. Find the focal length of the telescope's objective lens.
    Solving the problem:
    Angular magnification:
    M(ang.) = 3.10 10-3 rad. / 8.0 10-5 rad. = 38.75 x
    Objective focal length:
    f'(ob) = 38.75 * 37(eyepiece focal length) = 1433.75 mm.
    Telescope magnification:
    M = f'(ob) / eyepiece focal length = 1433.75 / 37 = 38.75 x

 

 

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