Change the chapter
Find the distance between the objective and eyepiece lenses in the telescope in the above problem needed to produce a final image very far from the observer, where vision is most relaxed. Note that a telescope is normally used to view very distant objects.
Question by OpenStax is licensed under CC BY 4.0.
$d \lt 102.5\textrm{ cm}$
Solution Video

OpenStax College Physics for AP® Courses Solution, Chapter 26, Problem 34 (Problems & Exercises) (1:12)

Sign up to view this solution video!


No votes have been submitted yet.

Quiz Mode

Why is this button here? Quiz Mode is a chance to try solving the problem first on your own before viewing the solution. One of the following will probably happen:

  1. You get the answer. Congratulations! It feels good! There might still be more to learn, and you might enjoy comparing your problem solving approach to the best practices demonstrated in the solution video.
  2. You don't get the answer. This is OK! In fact it's awesome, despite the difficult feelings you might have about it. When you don't get the answer, your mind is ready for learning. Think about how much you really want the solution! Your mind will gobble it up when it sees it. Attempting the problem is like trying to assemble the pieces of a puzzle. If you don't get the answer, the gaps in the puzzle are questions that are ready and searching to be filled. This is an active process, where your mind is turned on - learning will happen!
If you wish to show the answer immediately without having to click "Reveal Answer", you may . Quiz Mode is disabled by default, but you can check the Enable Quiz Mode checkbox when editing your profile to re-enable it any time you want. College Physics Answers cares a lot about academic integrity. Quiz Mode is encouragement to use the solutions in a way that is most beneficial for your learning.

Video Transcript
This is College Physics Answers with Shaun Dychko. We have a telescope that has an objective focal length of 100 centimeters and an eyepiece focal length of 2.50 centimeters and because these focal lengths are both positive, we know the type of telescope we are working with is one that has two convex lenses— the concave lens would require a negative focal length. So we have two convex lenses and the question is what is the distance between the objective lens and the eyepiece lens? So in this scenario, we know that the image produced by the objective has to be at this position between the focal point of the eyepiece and the eyepiece lens and we are trying to find this total distance between the objective and the eyepiece and so we know that this total distance has to be something less than the focal length of the objective plus the focal length of the eyepiece and so we know that this distance has to be somewhat less than 100 centimeters plus 2.50 centimeters or something less than 102.5 centimeters.