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When there is a very low voltage (AC), even for a compact fluorescent lamp (CFL), it glows very dim (orangish in color) at the beginning of the glass but when I hold the glass just for a second, it starts glowing as usual (generally white in color, don't know what your's is) though a very little bit dimmer than its original capacity. So, I want to know why it happens, i.e. it starts glowing at the same voltage when we touch it (the one I am trying is rated 220V, AC Current freq here is 50Hz, power required doesn't matter as it happens with all of them, voltage is ~30 in my case but it may differ in yours). If it's related to body-heat (because I think so), why does it just keeps glowing continuously even if we don't touch it after that?

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  • \$\begingroup\$ Welcome to EE.SE. People won't downvote "cause you haven't faced it" but they will downvote if your question isn't clear. Add a photo of the lamp and show where you are touching it. You might also state the voltage rating of the lamp and the voltage during the test. \$\endgroup\$ – Transistor Jan 31 at 17:25
  • \$\begingroup\$ Sorry mate, can't add an image. Don't have enough reputation points. And as far as the rating is concerned, I am just gonna edit it in a moment \$\endgroup\$ – Gaurav Jan 31 at 17:29
  • \$\begingroup\$ I have actually seen something similar - an off CFL flashing when I touch it. I explain it to myself wit static electricity... \$\endgroup\$ – Eugene Sh. Jan 31 at 17:32
  • \$\begingroup\$ What do you mean by "voltage is ~30"? What voltage is this, and where are you measuring it? At one point you say "hold the glass" and at another point you say "touch it"...these are different, can you clarify? \$\endgroup\$ – Elliot Alderson Jan 31 at 18:13
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    \$\begingroup\$ By '~', I meant 'almost' and unit is 'Volts'. And sorry for unclarified question, if you say so. When I say 'hold the glass' or 'touch it', I mean 'touch glass portion for a few moments not an instant'. BTW, I'd go with your answer @mike65535. \$\endgroup\$ – Gaurav Jan 31 at 18:32
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Sounds like you are "striking an arc" with static electricity by touching it - setting off the gas to become a "electrically conductive medium" which is how a fluorescent bulb normally works. The glow is maintained by the low AC voltage at that point - just not as well as the correct voltage.

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    \$\begingroup\$ Worth noting is that this is actually a pretty common demonstration in freshman science classes, but with a long fluorescent tube rather than a CFL. And generally in a dark room. \$\endgroup\$ – Hearth Jan 31 at 21:43
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Interesting observation, I will take a guess, since I cannot reproduce. AFAIK, those kind of lights operate on the principal of avalanche. The system has two equillibria, one in which the population of electrons is not enough to trigger an avalanche in which the collective motion of electrons are enough to create a bright light, and the other that is enough. I think bu contact, either by the warmth of your hand, or better contact with the conductors due to jiggling, you move the system from one equilibrium to other. And after that, there is no turning back, because the electron motion is enough to sustain operation.

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