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### Course: Optics (Essentials) - Class 12th>Unit 3

Lesson 6: How telescopes work

# How telescopes work

Let's explore how telescopes work intuitively using a demo. Then we will talk about some nuances involved in drawing ray diagrams and derive an expression for magnifying power.  Created by Mahesh Shenoy.

## Want to join the conversation?

• can't the real image be obtained only on a screen, how can you say that the image formed by the first lens (in the demo) is a real one, as it could be seen without the screen?
• He may have captured it on the camera screen. Btw your retina is also a screen.
• when you showed the moon with simple microscope it was blurred as you said but why is it enlarged. you told it wont enlarge right?
• At , the teacher states that light that goes through the optic center passes undeviated and I am familiar with it as well. But the rule seems somewhat unintuitive to me. Can anyone please help me on this? Thank you!
(1 vote)
• Im back with a lot of research, so wats the big deal is that light ray passes through optic center because we use extremely thin lenses and the deviation it undergoes in refraction is almost negligible
(1 vote)
• I don't understand. Weren't the magnifying glass and the objective both convex lenses with limited focuses, so why does one produce a clear image and the other a blurred one?
(1 vote)
• how do we view an erect image? the image shown after the telescope set up is inverted.
(1 vote)
• how does the image made by the object lens turn into an image that hits the eyepiece?
(1 vote)