For the telescope described in Exercise 9.34 (a), what is the separation between the objective lens and the eyepiece?

Given:

Focal length of the objective lens, f₀ = 140 cm

Focal length of the eyepiece, f_e = 5 cm

In normal adjustment, the separation between the objective lens and the eyepiece

(The rays striking the objective lens are coming from infinity hence they are converged at the focus by objective lens, a small image is formed at focus of objective, the eyepiece magnifies the image at it focus, hence the length of telescope or distance between the objective and eyepiece is f_e + f_o)

d = f_o + f_e

⇒ d = 140 + 5

⇒ d = 145 cm