Question

(a) Draw a ray diagram depicting the formation of the image by an astronomical telescope in normal adjustment.

Or

(b) You are given the following three lenses. Which two lenses will you use as an eye piece 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

Answer 1

(a)

(b) For eye piece, we use L₃ as it has high power and hence more magnification.

For objective, we use L₁ as it has high aperture and hence high resolving power.