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On Mon, 7 Oct 1996 22:09:23 -0400 Ken Becker <[log in to unmask]> wrote: >> I have a theory about the effect of artificial light, which runs on an >> alternating current power supply (our normal power lines in the US run >> at 60 Hertz, actually turning all lights run from it on and off 60 times >> per second. ) ... >> Does anyone else have any inside info on this phenomenon? Ken: It's not "inside info", but I do have a few barely connected thoughts on the subject. The 60 Hz "flicker" is much more pronounced in flourescent and "neon" lights than in incandescent ones. I'm tempted to say that it's completely absent in incandescent bulbs. The reason is that the incandescent light comes from a "white hot" filament, that's heated by the current. It's true that the filament receives zero current at 120 points during each second (in the U.S., at least), and somewhat reduced current for about 1/2 of each second in all, but the "switch-ons and switch-offs" come too fast for the filament to cool down very much, so its light output doesn't really fluctuate. The electrochemical mechanisms of the flourescents respond a lot more quickly to the electrical fluctuations, so you can perceive the flicker more easily. It might be interesting to compare the effects of incandescent and flourescent light sources. (One confounding factor: Flourescents give off light that's "bluer" than incandescents. If the color of the light is a factor, this would be a problem.) For what it's worth your computer screen also flickers at something closer to 30 times per second. (I also know that flickering lights can also produce seizures in epileptics, though I don't think the happens in the 30-60 Hz range.) Thanks for indulging me, everyone. Hope someone found this interesting.