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.

Q. (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.

Q. You are given following three lenses. Which two lenses will you see as an eyepiece and as an objective to construct an astronomical telescope?

Lenses	Power	Aperture
$L_1$	$3D$	$8cm$
$L_2$	$6D$	$1cm$
$L_3$	$10D$	$1cm$

Q. From the following three lenses, which two lenses will you use as an eyepiece and objective lens, to construct an astronomical telescope?

Lenses	Power	Aperture
$L_1$	$3\text{D}$	$8\text{cm}$
$L_2$	$6\text{D}$	$1\text{cm}$
$L_3$	$10\text{D}$	$1\text{cm}$

Q. From the following three lenses, two lenses are used as an eyepiece and the objective lens, to construct an astronomical telescope. Find the angular magnification for the normal adjustment.

Lenses	Power	Aperture
$L_1$	$3\text{D}$	$8\text{cm}$
$L_2$	$6\text{D}$	$1\text{cm}$
$L_3$	$10\text{D}$	$1\text{cm}$

Q. (a) Draw a labelled ray diagram to obtain the real image formed by an astronomical telescope in normal adjustment position. Define its magnifying power.

(b) You are given three lenses of power 0.5 D, 4 D and 10 D to design a telescope.

(i) Which lenses should be used as objective and eyepiece ? Justify your answer.

(ii) Why is the aperture of the objective preferred to be large ?