“Do you know, polarisers [circular polarisers] only work in one direction,” clearly a myth propagated by someone whose education in the arts had kept them away from even basic physics.
However, it’s true. What’s more if you hold a circular polariser up to a mirror, just a few inches from your eye, it’s clear the correct way round and dark the wrong way round. Me doing this below:
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| Looking into a mirror with the polariser the correct way round – clear | Looking into a mirror with the polariser the wrong way round – dark. |
This doesn’t happen with a linear polariser which works exactly the same either way round. What’s going on?
Explanation below.
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