Late night thunderstorm - lightning appeared to hit less than a few hundred feet from house. Immediate effect - light in hall (ordinary bulb dimmed) went out, although electric power was still on (electric clock still working). Ten minutes later light in hall comes back on. How can an ordinary light bulb behave this way?
You say "ordinary bulb dimmed" - what type of bulb are you considering is "ordinary"? Is it a compact flourescent light bulb (i.e. energy saving flourescent)? I ask as it sounds like the sort of thing you might get with an overheating transformer. I.e. it overheats and cuts out, then cools and cuts back in.
Bulb blew out; the surge blew out a part of the filament and broke the connection. The filament then cooled and made contact again.
way more statistically likely than baldees idea of harmonic discordance of frequency in the wiring & atmospheric static electricity, though has been noted many times.
I assumed a plain incandescent bulb on a switch. Once you introduce electronics (a dimmer switch, a compact fluorescent ballast, an LED bulb) all bets are off.
fluorescent with onboard starter etc.... these days ordinary could be a kerosene lamp or a computer controlled LED lol
Well, I've had one with an overheated transformer and none with the broken filament. So taking that as a perfectly adequate sample size, I can readily conclude that the transformer issue is infinitely more likely than the filament issue. Please Register or Log in to view the hidden image!
Bulb was old fashioned incandescent 60 watt. Switch was on dim. Distance to lightning bolt was short enough that there was no time between lightning flash and thunder. billvon answer seems most reasonable, even if improbable.
that you should probably check your wiring to make sure its ok. dimmers are notorious for causing issues(shorts carbonising, fires etc)
the light is always brighter when it re-joins it then burns out in a few days or a week or 2. assuming it doesn't cook the glass and explode(which can also happen) with a pop(heard that happen a few times) realy annoying when it pops when your out and you then walk on the broken glass barefoot and have to dig a piece of glass out of your foot. worst case scenario... what is probably more likely is you have a wiring fault in your roof electrical system that may start a fire in your house. the increased surge of electrical current has fed up your earth and incoming wiring(pole fuse didn't go?! ut-oh... breakers didnt go ? ut-oh) super heated some wire somewhere that has burnt out then re-joined as it cooled. it may start a fire eventually. testing the light socket would seem mandatory if you don't want your house to burn down.
Know? Not sure I know for sure, but it was a CFL and overheating of the transformer was the most likely explanation. Certainly not the filament... ... as it doesn't have one. Please Register or Log in to view the hidden image! Note, I offered my explanation before knowing what kind of lightbulb it was. Please Register or Log in to view the hidden image!
You should get five SciForums members to change it - one to change the bulb and four to give different opinions on how it should be done.