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Question
You are given the following three lenses. Which two lenses will you use as an eyepiece and as an objective to construct an astronomical telescope ? Give reason
| Lenses | Power (D) | Aperture (cm) |
| L1 | 3 | 8 |
| L2 | 6 | 1 |
| L3 | 10 | 1 |
Solution
For a telescope, lens L1 is chosen as objective, as its aperture and focal length are largest.
The lens L3 is chosen as eyepiece as its focal length is smallest.
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