A) 76 cm and 4 cm
B) 95 cm and 5 cm
C) 85 cm and 15 cm
D) 82 cm and 18 cm
Correct Answer: B
Solution :
Key Idea: To see with relaxed eye final image should be formed at infinity. Distance between the two lenses is \[{{f}_{a}}+{{f}_{e}}=100\,\,cm\] ?(1) Also magnifying power \[M=-\frac{{{f}_{o}}}{{{f}_{e}}}=-19\] \[\Rightarrow \] \[{{f}_{o}}=19\,\,{{f}_{e}}\] ?(2) From Eqs. (1) and (2), we get \[{{f}_{e}}=5\,cm,\,{{f}_{0}}=75\,cm\] Note: objective of telescope is taken large so that sufficient light is collected and a bright image is formed, while eyepiece is taken small so that whole light is collected at eyepiece, therefore\[{{f}_{0}}>>{{f}_{e}}\].You need to login to perform this action.
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