Multiple Plane Mirrors: How Many Images Will Be Formed?

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SUMMARY

The discussion centers on the calculation of images formed by three plane mirrors positioned on adjacent walls and the ceiling of a room. The initial claim of nine images is corrected to seven images based on the principle that each mirror doubles the number of objects. Specifically, with three mirrors, the formula 2^3 - 1 is applied to account for the real object, resulting in a total of seven distinct images. The importance of visualizing the arrangement through a diagram is emphasized for clarity.

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  • Understanding of geometric optics principles
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  • Basic knowledge of combinatorial mathematics
  • Ability to interpret and create geometric diagrams
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Students studying physics, particularly in optics, educators teaching geometric optics, and anyone interested in the mathematical aspects of reflections and images formed by mirrors.

sachin123
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Homework Statement



How many images of a symmetrically placed object will be formed if 2 plane mirrors are fitted on ADJACENT walls of a room and another one on the top(roof)?
(mirrors are big)

2. The attempt at a solution
According to me,9.
because,3 direct images of the object are formed by the 3 mirrors.And the image formed by each mirror serves as an object for the other 2 mirrors thus forming 2 x 3 = 6 more images,thus a total of 9 images.

Am I correct?
 
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Not exactly. Try drawing a diagram. Each mirror doubles the system. So three mirrors would create 2^3 objects total. The question asks for images, so we must subtract the real objects which is not an image: 2^3 - 1 = 7 images. You have over-counted the cross images by neglecting the fact that they line up and become the same image.
 

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