When an astronomical telescope is in normal adjustment, the focal length of the objective lens is 50cm and that of the eye piece is 5.0cm. What is the distance between the lenses?
10.0cm
30.0cm
45.0cm
55.0cm
250.0cm
Correct answer is D
An astronomical telescope is said to be in NORMAL adjustment when the distance between the objective lens and the eyepiece equals the sum of their focal lengths.
hence,
D = F\(_{e}\) + F\(_{o}\)
= 50cm + 5cm
= 55cm