# Homework Help: Ray diagrams for an astronomical telescope

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1. May 24, 2013

### [KNIGHT]

1. The problem statement, all variables and given/known data
An astronomical telescope is constructed using 2 convex lenses. The objective lens is of focal length 40cm and eyepiece lens is of focal length 10cm. Let d be the distance between the 2 lenses. Draw ray diagrams for the following situations.
1.When d=50cm
2.When d>50cm
3.When 40cm<d<50cm
The telescope is used to observe objects at infinity.

2. Relevant equations

3. The attempt at a solution
In each situation I drew the objective lens's incident ray and the refracted ray up to its focal plane. But i do not understand how to complete them.

2. May 24, 2013

### rude man

The objective lens creates an image (what kind?) where? So the eyepiece should be positioned where to create parallel rays for the eye to focus on its retina?

3. May 24, 2013

### barryj

The image from the objective lens will be the object for the eyepiece. Using this object, draw the rays to form the image from the eyepiece.