I have one of those cheap brandless RGB LED strips connected to my ceiling. One of the first things I noticed about it is that when it's blue a lot of objects in my room give that weird glow that you get with UV black lights. Specially orange things. And some things just change color.
So I figured this thing is actually giving off UV.
Yesterday I was lying in my bed and stared at them for like 15 minutes. Afterwards I felt my eyes are hurt. They still feel hurt today. (The lights are music reactive and were also flashing frequently).
So I was wondering if it's possible for these strips to give off UV. Possibly dangerous amount of UV.
Should I be worried?
I doubt it. It's possible the blue leds are giving off a little UV in the longer wavelength end of the UVA band, but these are the least dangerous types of UV. The more likey reason for your eyes hurting is staring at flashing lights for 15 minutes.
The fluorescent effect applies to light of all colours not just UV. Have you seen those glow in the dark stickers or the luminous dials on watches? They use the same effect with viable light exciting electrons into what is known as a quasi stable state. They then exponential decay and each decay produces a photon.
Grumpy_Mike:
The fluorescent effect applies to light of all colours not just UV. Have you seen those glow in the dark stickers or the luminous dials on watches? They use the same effect with viable light exciting electrons into what is known as a quasi stable state. They then exponential decay and each decay produces a photon.
This is what I mean. See how the yellow wire is glowing?
You can go here to see it under normal light.
There's nothing fluorescent involved. It's normal stuff glowing under the blue light of the strip. As they do under "black light", aka UV light. It's actually more intense than it looks in the pics. Everything white also glows a little.
What Mike means is that the wire is exhibiting florescence. Absorbing light of one colour and emitting light of a different colour. It may not have been designed to do that, but some materials have that natural property.
Yes there is. It is a propriety of all materials. It is just that some materials have more quasi stable states in their structure than others. It is not an indication that there is UV light coming off your LEDs.
As they do under "black light"
The fact that they will do it under UV light is just because a photon of UV light contains more energy than a photon of blue light so it is more likely to excite an electron from the material into a higher energy state. When these states decay they can decay into a quasi stable energy level or a ground energy level where they started from.
This is all simple physics, I was a senior lecturer in Physics at a UK University, a post that people in the U.S. and other places, would call a professor.
I did a project in October 2019 on how to measure these effects using a Raspberry Pi, available as a free PDF download at:- https://magpi.raspberrypi.org/issues/86
You should be able to convert it to use an Arduino if you want to have a go. You can use different LEDs to look at the phosphorescence effect on different materials. It also tells you the difference between phosphorescence and fluorescence.
