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JEE Main & Advanced Physics Ray Optics Question Bank Microscope and Telescope

  • question_answer
    In a terrestrial telescope, the focal length of objective is 90 cm, of inverting lens is \[5\,cm\]and of eye lens is \[6\,cm.\]If the final image is at 30 cm, then the magnification will be  [DPMT 2001]

    A)            21  

    B)            12

    C)            18  

    D)            15

    Correct Answer: C

    Solution :

               \[m=\frac{{{f}_{o}}}{{{f}_{e}}}\left( 1+\frac{{{f}_{e}}}{D} \right)\Rightarrow m=\frac{90}{6}\left( 1+\frac{6}{30} \right)\Rightarrow m=18\]


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