Why do CFl lightbulbs tend to glow after being turned off

I noticed this a few times but never really thought about it....
Like, i go to the bathroom at about 1:30 (i have insomnia) and when i come back, i turn on the light for a few seconds just so i see where i can step without slipping and smashing my tailbone.

So, why do CFl lightbulbs glow after being turned off?

Awesome question! CFL stands for Compact FLUORESCENT Light. The fluorescent bit is the important part. Think back to what you know about the structure of the atom. There is a central nucleus, and then outside the nucleus are the electrons. You can think of them as orbiting the nucleus (this is not exactly correct, but this description will suffice). OK, remember those electrons. Second, if you have ever broken a CFL light bulb (not recommended) it is full of white powder. The bulb sends electric current into this white powder. The atoms of the white powder respond when they are placed in a current, and the electrons orbiting the nucleus jump up to a higher orbit around the nucleus. After staying there for a bit, they fall back down to their original orbit and when they do this, they emit a photon, or 1 particle of light! Now, multiply that by millions and millions of atoms inside the light bulb, and these emitted photons are what make the light, um . . .light up. Now, when you shut off the electric current (like by turning the light off), lots of electrons are still in their higher orbits, or "excited states" as they are called. It takes some time for the electrons to return to their lower orbits, and as they do that the light continues to glow, until all the electrons have relaxed. This process of continued glowing is fluorescence.

What is really cool is that if you have a black light, lots of different rocks do exactly the same thing. Take a black light out some time at night and you will probably be surprised by what you find.

The phosphors used to convert ultraviolet light to visible light have a property called persistence, some more than others, depending on the tint of the CFL and the manufacturer. Neil