eli5: Why does a magnifying glass flip the image after a certain distance from the eye?
In: Physics
Just like two people will end up on opposite sides of each other after their paths cross, the two ends of a light beam do the same thing. After all, a lens takes a certain image and changes the paths of the photons. At a certain distance, they will come together and form a sharp image for your eyes (or for burning stuff if you’re that kid) at the “focal point.” But farther away than that, the light beam will have crossed paths with itself and become upside down/backwards.
Think about what the lens is doing. It’s taking light from all parts of the object and focusing it toward a point in space. The light from the top is going toward the center. The light from the bottom is going toward the center.
What happens when the light goes past that point, though?
The light that started at the top of the object will be on the bottom. Likewise for the light at the bottom now being at the top.
Of course, the image will quickly lose focus as the light gets further away, but that’s the idea.
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