Why is the image formed next to the object?

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  • Thread starter Thread starter Wasif Shah
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Discussion Overview

The discussion revolves around the formation of images by mirrors and lenses, specifically addressing why the image appears next to the object rather than directly overlapping it. The scope includes conceptual understanding and practical implications in optics.

Discussion Character

  • Conceptual clarification, Technical explanation

Main Points Raised

  • One participant questions why the image formed by a plane mirror does not overlap the object, despite light rays reflecting back along the same path.
  • Another participant suggests that if the lens and mirror are parallel and the lens axis passes through the object's center, the image can be positioned slightly to the side for practical purposes.
  • A participant expresses confusion about the practicality of having the image not overlap the object and seeks clarification on how the image is produced next to it.
  • Further elaboration is provided on how rotating the mirror can cause the image to form to the side due to the angle at which light rays enter the lens.
  • One participant expresses gratitude and indicates understanding of the explanation provided.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the image formation process, with some confusion remaining about the practical implications of image positioning. No consensus is reached on the conceptual clarity of the topic.

Contextual Notes

The discussion includes assumptions about the alignment of optical components and the effects of angle on image formation, which are not fully resolved.

Wasif Shah
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According to this passage the image of an object after being reflected by a plane mirror is formed right next to the initial object position. However if you see the light rays, they come back exactly the same path after striking the mirror, then why doesn't the image also forms right on top of the illuminated object (cross wire), and instead forms on the side?
 
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Your intuition is completely correct if the planes of lens and mirror are exactly parallel AND the lens axis goes through the center of the object.
But to perform this determination of the focal length, it is very practical if the image is not exactly on top of the object, but a bit to a side.
This can be achieved by shifting the lens a little bit sideways.

You can convince yourself by drawing a top view of the image formation with an off-axis object.
 
Nope I don't get it :/ . Esp the last part when you said 'it is very practical if the image is not exactly on top of the object, but a bit to a side'

How is the image even produced next to it? I feel it should exactly overlap the object. :/
 
Wasif Shah said:
Nope I don't get it :/ . Esp the last part when you said 'it is very practical if the image is not exactly on top of the object, but a bit to a side'

How is the image even produced next to it? I feel it should exactly overlap the object. :/

Suppose you took the layout as shown in your diagram and rotated the mirror slightly about a vertical axis. Then the parallel rays that leave the mirror would enter the lens at a slight angle with respect to the parallel rays leaving the lens. As a result, the image will form a little to the side of the light. Typically you would hold a screen (such as a sheet of paper) next to the light and move the lens toward or away from the light until a sharp image forms right next to the light. Then you know the lens is a focal length away from the light.
 
Thankyou soo much I get it <3 :)
 

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