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Basically not exactly a homework, but I came across this problem. I have two plane mirrors angled at 60 degree angle. An object is placed in between symmetrically. What will be the number of total images obtained?

What I mean is that there will be images of images, how can we count them (If at all), and how are they related to angle between the mirrors? Any help will be appreciated.

enter image description here

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up vote 2 down vote accepted

You can solve this problem the same way that you solve most problems with compound optical systems in simple geometrical optics, that is:

  1. Find the image(s) produced by the first element in the system
  2. Use those images as the objects for the next element in the system, find the resulting images.
  3. Repeat step 2 as neccesary.

In this case, there is a complication due to the fact that you essentialy have two paths in parallel to keep track of. More explicitly, find the images in each of the mirrors. Next, using those images as objects, find their images in the other mirrors. You will see that due to the geometry, at a certain point, you will run out of objects, because there are no more images generated in front of a mirror.

See also for some helpful diagrams and pictures.

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