For the 2nd time I've had a lightbulb flash on in my hand after removing from the power socket. The first time the overhead light in my hallway was out for a couple of days before I got around to changing it. This was a cfl bulb and after I unscrewed it and was making my way down the ladder it flashed back on in my hand for about 3 seconds and went back out. I decided to put it back in the fixture and it went back to working. It's now approximately 4 months later and again the bulb went out. I unscrewed from the socket, had the tube end in my hand coming down the ladder when it again flashed on briefly and went back out. I tried putting it back in the fixture and again it has gone back to working. I don't know what to make of this as I've been unable to find any explanation as to how this can happen. What could make a disconnected bulb light up in my hand without any power source? Any thoughts?
[Physics] Light bulbs flashing on when disconnected
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Related Solutions
Old fashioned (or very cheap) fluorescent bulbs flicker at twice the mains frequency if they use magnetic ballasts driven directly from the AC. Modern fluorescent bulbs use an electric ballast that runs at 5khz - 40khz (for CFLS), then the electrons stay excited for longer than the switching frequency and the light output is constant.
LEDs are constant, unless you count the individual electrons moving over the diode junction! High power LEDs normally have their own driver chip which carefully controls the current and voltage of the diode so they are less sensitive to the supply power.
Solid state lasers are essentially the same as LEDs.
edit: some very cheap LED lights, eg christmas decoration are driven directly from AC - using the diodes themselves to rectify it - these will flicker at the 1/2 mains frequency.
Here is a comparison chart. The number don't correlate exactly since there are differences in the manufacturing of the bulbs.
Best Answer
Flurescent light bulbs are known for the way they light up when subjected to static electricity. Here is a video of an instructor using a Van de Graaff generator to light up an old fashioned fluorescent light. CFLs are just old fashioned fluorescent bulbs bent into a different shape with a DC power supply tacked on.