Sunglasses filter out certain types of light… basically light has different wavelengths which correspond to different energies – and in visible light, different colours. At energies slightly higher than blue (ie beyond what we can see with the naked eye) you get ultraviolet (UV) light. There’s a lot of UV light in sunlight and it’s this high energy light that damages our eyes. So sunglasses work by having a special coating that doesn’t allow light with UV wavelengths to penetrate…
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