For a distant object,the angular magnification of an astronomical telescope is $5$. The distance between the objective and the eyepiece is $36 \, cm$,and the final image is formed at infinity. What are the focal lengths of the objective $(f_o)$ and the eyepiece $(f_e)$?

  • A
    $f_o = 45 \, cm$ and $f_e = -9 \, cm$
  • B
    $f_o = 50 \, cm$ and $f_e = 10 \, cm$
  • C
    $f_o = 7.2 \, cm$ and $f_e = 5 \, cm$
  • D
    $f_o = 30 \, cm$ and $f_e = 6 \, cm$

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