I already know that visible light is only a tiny fraction of the electromagnetic spectrum, and just after that comes UV radiation, since its wavelength is shorter and thus frequency is higher. My question is: if you can ONLY see visible light, then why can you often see UV light as purple? Isn’t it supposed to be invisible? I’m referring to those commercial torches that emit UV (and purple) light.
In: Physics
First, to answer you question as best I can:
The UV light component is invisible, but the light source also emits visible violet light. I don’t know whether that’s a physical limitation or a safety issue (if you can’t see the light, you can’t tell if it’s on).
Second, it’s violet, not purple. Violet is its own color, with a specific wavelength range. Purple is a mix of two or more colors (reds and blues), each with their own wavelength. To our eyes, it’s a subtle difference, but they’re thus very different on the physical level.
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