A) 98 cm
B) 198 cm
C) 298 cm
D) 3 m
Correct Answer: B
Solution :
In Galilean telescope, a convergent lens is used as the objective and a divergent lens as the eyepiece Magnifying power and length of telescope are written as \[M=\frac{{{f}_{o}}}{{{u}_{e}}}\]and \[L={{f}_{o}}-{{u}_{e}}\] In normal adjustment, \[{{u}_{e}}={{f}_{o}}\] So, \[{{M}_{\infty }}=\frac{{{f}_{o}}}{{{f}_{e}}}=100\] or \[{{f}_{e}}=\frac{{{f}_{o}}}{100}=\frac{200}{100}=2\,cm\] and \[{{L}_{\infty }}={{f}_{o}}-{{f}_{e}}=200-2=198\,cm\]
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