Q 9.29 (b) 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?
focal length of the objectove lens = = 140cm
focal length of the eyepiece lens = = 5 cm
Height of tower = 100m
Distance of object which is acting like a object = 3km = 3000m.
The angle subtended by the tower at the telescope
Now, let the height of the image of the tower by the objective lens is .
angle made by the image by the objective lens :
Since both, the angles are the same we have,
Hence the height of the image of the tower formed by the objective lens is 4.7 cm.
Create Your Account