Calculating Number of Images in Mirrors

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Discussion Overview

The discussion revolves around calculating the number of images formed by two mirrors at various angles (20, 30, 40, 60, 90, and 0 degrees). Participants explore theoretical approaches and practical considerations related to this phenomenon.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asks about the number of images formed by two mirrors at different angles and seeks an equation for this calculation.
  • Another participant points out the absence of an observer in the initial image, suggesting that the presence of an observer is necessary for the discussion.
  • A participant suggests that the same number of images would be formed on each mirror, regardless of the observer's position.
  • One participant proposes a formula for the number of images as (360/angle - 1), noting that non-integer results indicate images may be cut by the junction between the mirrors, affecting visibility based on the observer's position.
  • Another participant requests clarification on how the formula was derived.
  • A detailed method is suggested involving drawing reflections and counting images, along with practical experimentation with mirrors.
  • A novice participant raises a question about the role of photon intensity in determining detectable reflections within the mirrored angle set.
  • Another participant comments on the diminishing visibility of images due to less than 100% reflection efficiency of mirrors and discusses the properties of dielectric mirrors that can reflect nearly all light.

Areas of Agreement / Disagreement

Participants express various viewpoints on the calculation of images and the factors affecting visibility, indicating that multiple competing views remain without a consensus on the best approach or understanding.

Contextual Notes

Some assumptions about the observer's position and the nature of reflections are not fully explored. The discussion also touches on the limitations of mirror reflectivity and its impact on image visibility, which remains unresolved.

gazepdapi1
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I need some help guys with this one. Say you have two mirrors like in the image below, with some angle phi between them. The question is how many images would be formed if the angle between them changed to 20, 30, 40, 60, 90, or 0 degress. Is there some sort of equation that will give you this?
thanks a lot.
nertil1http://img139.imageshack.us/my.php?image=untitledwy0.jpg"
 
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There is no observer to observe any images in that pic. :confused:
 
Yeah sorry, imagine there is an observer looking at the vertical mirror, although I don't think it would matter because the same amount of images would be formed on each mirror, I think.
thanks
 
The number of images is (360/angle -1). When the result is an integer, all is OK. When it is no the case (say, 3.65) it means that some images are "cut" by the junction between the mirrors and that what you see depends on the position of the observer.
 
thanks a lot man but can you show me how you derived that formula please?
 
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Draw the image of each mirror reflected on the other one. Draw the image of the mirror and their images reflected by the mirrors and their images. Repeat this until you fill the plan.
You will see the pan divided in angles equal to the angle between mirrors. If the angle does not divide 360° exactly, there will be "a problem" in the opposite side to the middle of the mirrors.
Now draw an object between the mirrors rather near one of them. A small arrow perpendicular to the near mirror will do.
Draw the images of the arrow as reflected in each mirror. Draw the reflected images of all the arrows (real and images) in all the mirrors. Count the images.
Do this for angle = 180° (equal to a single mirror), 90°, 60°, 45°, etc. count each time. Extrapolate.
But, better that all this, take two mirrors and watch what you see as the angle changes.
 
As a novice, I yet ponder if the photon intensity of the initial and subsequent reflections largely determine the number of theorectically detectable reflections within a given mirrored angle set.
 
When there are a lot of photons there is no need to talk about them. They behave as a whole.

Current mirrors do not reflect 100% of the received light. They only reflect about 92-94%.
Then after several reflections, images dim. Moreover, in back-silvered mirrors, light must traverse twice the front glass. After several reflections, you began to see the images get greener and greener. You can see this, locking at the reflections of two mirrors forming a small angle.

Physicist know how to make mirrors that reflect almost 100% of the light. They are built as a super sandwich of dielectrics of controlled thickness. They are called "dielectric mirrors".
 

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