How Do Mirrors Create the Infinity Effect?

Mirrors are surfaces that reflect light. When two mirrors face each other, they create what we call an “infinity mirror effect.” Here’s why:


Imagine you stand between two mirrors. When you look into one mirror, you’ll see your reflection. But you’ll also see the reflection of the other mirror behind you. And in that reflection, you see a smaller reflection of yourself, and behind that, another reflection of the mirror. This goes on and on, creating a series of smaller and smaller reflections that seem to go on forever!


This has to do with a formula that relates the number of images formed by two mirrors with how these mirrors are positioned. The formula is:


N= 360/θ-1, where N is the number of images formed, and θ is the angle between the mirrors.


When two mirrors face each other, the angle between them is 0°. Anything divided by zero is considered to be infinite, hence we get infinite images when two mirrors face each other.


But they don’t go on forever. Each time light bounces between the mirrors, a tiny bit of it gets absorbed or scattered. So, with each reflection, the image gets a little dimmer.


Here’s a numerical example: if a mirror reflects 95% of the light (this is pretty good for a household mirror) and absorbs 5%, after 10 reflections, only about 59% of the original light remains. After 50 reflections, less than 7% remains. So, while there seem to be endless reflections, they eventually fade away due to the tiny losses with each bounce.


So, facing mirrors give us a cool optical effect, showing us how light can bounce back and forth and create a seemingly infinite tunnel of reflections.


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