The document describes the construction and working of an astronomical telescope using convex lenses of focal lengths 10 cm and 30 cm. It explains how to construct the telescope using the lenses and calculates the magnification of the telescope as -4.2 for an image at the minimum distance of distinct vision and -1.2 for an image at infinity. The conclusion states that the telescope can produce real, inverted and magnified images of distant objects.

1. Aim
To understand the construction and working of an astronomical telescope using
convex lenses of suitable focal lengths.

2. Introduction

3. Apparatus used
Convex lenses of focal lengths 10 cm and 30 cm
Ivory sheets
Adhesive tape

4. Theory and working
1.)Construction

5. 2.)Working of astronomical telescope

7. Magnification for the telescope made by two given lenses
fo = 30cm = 0.3m
fe = 10cm = 0.1m
D = 25cm = 0.25m
m = -
0.3
0.1
(1 +
0.1
0.25
) = -4.2 for image at least ditance of distinct vission
m = -
0.3
0.1
0.1
0.25
= -1.2 for image at infinity

8. Conclusion
The astronomical telescope designed is able to produce real, inverted and
magnified images of the objects very far away from it.
Sources of errors
Write yourself
Precautions
Write yourself
Bibliography
NCERT textbook of class 12
Physics by S.L.Arora
Designs available on internet