Share

# If this Telescope is Used to View a 100 M Tall Tower 3 Km Away, What is the Height of the Image of the Tower Formed by the Objective Lens? - CBSE (Science) Class 12 - Physics

#### Question

If this telescope is used to view a 100 m tall tower 3 km away, what is the height of the image of the tower formed by the objective lens?

#### Solution

Height of the tower, h1 = 100 m

Distance of the tower (object) from the telescope, u = 3 km = 3000 m

The angle subtended by the tower at the telescope is given as:

theta = h_1/u

= 100/3000 = 1/30 rad

The angle subtended by the image produced by the objective lens is given as:

theta = h_2/f_o = h_2/140 rad

Where,

h2 = Height of the image of the tower formed by the objective lens

1/30 = h_2/140

:. h_2 = 140/30 = 4.7

Therefore, the objective lens forms a 4.7 cm tall image of the tower.

Is there an error in this question or solution?

#### APPEARS IN

NCERT Solution for Physics Textbook for Class 12 (2018 to Current)
Chapter 9: Ray Optics and Optical Instruments
Q: 35.2 | Page no. 349
Solution If this Telescope is Used to View a 100 M Tall Tower 3 Km Away, What is the Height of the Image of the Tower Formed by the Objective Lens? Concept: Optical Instruments - Telescope.
S