Question

) If the focal length of objective lens of an astronomical telescope is
20 cm and the length of it is 25 cm, the magnification of the telescope
for normal adjustment is
(a) 5
(b) 4
(C)1.25
(d) 1​

Answer 1

Answer:

1.25 is the correct answer

Answer 2

Magnification = 1.25 for normal adjustment.

Given:

Focal length of objective lens of an astronomical telescope is

20 cm.

The length of it is 25 cm.

To find:

Magnification of the telescope for normal adjustment is.

Concept used:

The ratio of image distance to object distance or length of object to the  is  called as magnification.

Explanation:

• so from above definition,

            Magnification = $\frac{ length \ of \ object}{focal \ length\ of \ astronomical \ telescope}$

            Magnification =$\frac{25}{20}$

            Magnification = 1.25

Note: magnification has no unit it is simply a ratio of length of two different parameters.

Therefore, option (c) is the correct answer.

To learn more...

1. The magnification produced by three Mirrors A ,B and C are + 1, + 5 ,+ 0.45 respectively. Based on the magnification identify the mirrors. Which mirror can be used as dentist mirror ?

brainly.in/question/8035064

2. If a concave mirror of focal length 18 cm and magnification of 2 forms a real image of an object on its principal axis. Find the position of image.

brainly.in/question/14419073