Multiple Plane Mirrors: How Many Images Will Be Formed?

AI Thread Summary
When two plane mirrors are placed on adjacent walls and one on the ceiling, the total number of images formed can be calculated using the formula for multiple mirrors. Initially, three direct images are created by the three mirrors, leading to a potential total of nine images when considering reflections. However, the correct approach involves recognizing that each mirror effectively doubles the system, resulting in 2^3 total objects. Since the question specifically asks for images, the real object must be subtracted from the total, yielding 7 images. The initial count was incorrect due to over-counting overlapping images.
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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