EAMCET Medical EAMCET Medical Solved Paper-1999

  • question_answer
    An astronomical telescope has a length of 1.1 m and a magnifying power 10. The focal lengths of objective and eye lenses are:

    A)  0. 1 m and 1.0 m

    B)  1.0 m and 0.1 m

    C)  0.6 m and 0.5 m

    D)  0.5 m and 0.6 m

    Correct Answer: B

    Solution :

                     Given: magnifying power =10 The length of the astronomical telescope \[=1.1\text{ m}\] Length of telescope\[={{f}_{o}}+{{f}_{e}}\] \[1.1={{f}_{o}}+{{f}_{e}}\]                                           ?(i) Magnifying power of telescope \[m=\frac{{{f}_{o}}}{{{f}_{e}}}\]hence , \[\frac{{{f}_{o}}}{{{f}_{e}}}=10\]                                               ?(ii) or            \[{{f}_{o}}=10{{f}_{e}}\] Now, putting\[{{f}_{o}}=10{{f}_{e}}\]in Eq. (i) \[10{{f}_{e}}+{{f}_{e}}=1.1\]                 \[11{{f}_{e}}=1.1\Rightarrow {{f}_{e}}=\frac{1.1}{11}=0.1\,m\]                 So,        \[{{f}_{o}}=1m\]


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