An astronomical telescope has its two lenses spaced 81.1 cm apart. If the objective lens has a focal length of 78.0 cm , what is the magnification of this telescope? Assume a relaxed eye. Follow the sign conventions.

Answer :

Answer:

The magnification is  [tex]m = -26.16[/tex]

Explanation:

From the question we are told that

        The distance between the lenses is  [tex]L =81.1 cm[/tex]

         The focal length of the objective lens [tex]f_o = 78.0 \ cm[/tex]

Generally the  length of the telescope that satisfies the condition for a relaxed eye can be mathematically represented as

              [tex]L = f_0 + f_e[/tex]

Where [tex]f_e[/tex] is focal length of the eyepiece

      Making [tex]f_e[/tex] the subject the of the formula above

                [tex]f_e = L - f_o[/tex]

Now substituting value

               [tex]f_e = 81.1 - 78.0[/tex]

                   [tex]=3.1\ cm[/tex]

Generally magnification can be mathematically represented as

                            [tex]m = - \frac{f_o}{f_e}[/tex]

This negative sign is a reminder that all real image are always inverted

                                  [tex]=- \frac{81.1}{3.1}[/tex]

                                  [tex]= - 26.16[/tex]  

               

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