(c) In the refracting telescope given in the passage, what should be the distance between the two lenses? (Use the first ray diagram in the passage to answer it.)
- Incident light from infinity is being converged to a certain point by the first lens.
- Hence this distance is equal to the focal length of the objective lens.
- In the second lens, the light diverging from a point is being made parallel , also implying this point lies at the focus of the eye piece.
- Thus the 2nd part of the distance is the focal length of the second lens .
Thus, the distance between the 2 lenses is equal to the sum of the focal length of the objective and eyepiece .