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Question : 20
Total: 26
(a) Draw a ray diagram depicting the formation of the image by an astronomical telescope in normal adjustment.
(b) 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.
(b) 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) |
|---|---|---|
| | 3 | 8 |
| | 6 | 1 |
| | 10 | 1 |
Solution:
(a) Ray diagram for astronomical telescope in normal adjustment
(b) Identification of lenses for objective and eyepiece 1 Reason
(a) Ray diagram of astronomical telescope
(b) Objective Lens : LensL 1
Eyepiece Lens : LensL 2
Reason :
The objective should have large aperture and large focal length while the eyepiece should have small aperture and small focal length.
(b) Identification of lenses for objective and eyepiece 1 Reason
(a) Ray diagram of astronomical telescope
(b) Objective Lens : Lens
Eyepiece Lens : Lens
Reason :
The objective should have large aperture and large focal length while the eyepiece should have small aperture and small focal length.
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