What Determines the Size of an Image Formed at Infinity in Magnifiers?

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Discussion Overview

The discussion centers around the factors that determine the perceived size of an image formed at infinity when using magnifiers. Participants explore concepts related to lateral and angular magnification, as well as the role of the human eye in image perception.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions how an image formed at infinity does not appear infinitely large, referencing their physics book's claim that lateral magnification is not applicable in this scenario.
  • Another participant suggests that "infinity" is not a literal distance, but rather a large distance from the pole, indicating that the object is not exactly at the focus, which affects the perceived size of the image.
  • Some participants propose that the position and focal length of the mirror are key factors in defining the image size.
  • There is a discussion about the role of angular magnification versus linear magnification for distant objects, with a reference to external notes for clarification.
  • One participant emphasizes that the size of the image on the retina is determined by the angle at which light rays enter the eye and the eye's focal length.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and agreement on the concepts discussed, but no consensus is reached regarding the definitive factors that determine the perceived size of an image formed at infinity.

Contextual Notes

Participants reference the limitations of lateral magnification in this context and the need for angular magnification, but the discussion does not resolve the underlying assumptions or definitions related to these concepts.

kent davidge
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I was reading my physics book and I didnt understand how can a image formed at infinity does not appear to us as infinitely large. The book says that lateral magnification is not valid in this case. So what really defines how large a image is?
 
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First when we say infinity, it's not exactly "infinity"
It's a large distance from the pole, your object won't be exactly at the focus (practically)
so you won't have " infinitely large".
Infinitely large"- what does that actually mean?
What defines? It's the position and focal length of the mirror.
 
Yes, but I'm still trying to understand what in our eye determines how large an image will be. I'm showing you a image of the situation that caused my doubt. (sorry my bad english)
11t7bxl.jpg
 
kent davidge said:
I was reading my physics book and I didnt understand how can a image formed at infinity does not appear to us as infinitely large. The book says that lateral magnification is not valid in this case. So what really defines how large a image is?

In this case (distant objects and/or distant images), it's conceptually easier to use angular magnification rather than linear magnification to characterize the system:

http://physics.ucsd.edu/students/courses/winter2008/physics1c/documents/5.2OpticalInstruments.notes.pdf .

Does this help?
 
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kent davidge said:
Yes, but I'm still trying to understand what in our eye determines how large an image will be. I'm showing you a image of the situation that caused my doubt. (sorry my bad english)

Look at the picture on the right. The rays from the top of the inchworm enter the eye at angle θ. The eye then focuses the rays down onto the retina. The size of the image of the inchworm on the retina is determined by the angle at which the rays enter your eye and the focal length of your eye.
 

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