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Next to my bed I have a fluorescent desk lamp. One night, after I had turn off all the lights in my room, I grabbed my blanket from the other end of the bed. As I grabbed the blanket, one end of the blanket swept underneath my lamp. I was surprised to see a few faint flickers of light come from the light bulb. I tried waving the blanket underneath the lamp again and the same effect happened. I tried it again using my hand instead of the blanket, but the lamp did not flicker that time. Is there an explanation for this strange phenomenon? As a side note, the blanket never touched the bulb and it was swept about 6 to 18 inches underneath the bulb.

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  • $\begingroup$ The phosphor (the material that converts the generated UV into visible light) coating inside the tube often shows some residual glow, even after the current has been switched off. I think that's what you saw. $\endgroup$ – Gert Dec 6 '15 at 22:39
  • $\begingroup$ it was not a residual glow, but rather an abrupt flicker. I do know what you are talking about though, I have noticed the residual glow, but this was different from that :) @Gert $\endgroup$ – Ryan Dec 6 '15 at 22:42
  • $\begingroup$ Try doing the same motion with the lights off to determine whether or not it's actually the light $\endgroup$ – Zach Saucier Dec 7 '15 at 19:22
  • $\begingroup$ I did it with the all the lights off in my room. Even after the residual glow had faded away like gert mentioned above @ZachSaucier $\endgroup$ – Ryan Dec 7 '15 at 20:06
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I would guess that what you saw was due to static electricity. Your blanket must have been slightly charged and when you moved it below the bulb an induced emf caused the flicker of light.

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As I grabbed the blanket, one end of the blanket swept underneath my lamp.

"Swept" is the relevant word here. Wool or synthetic wool is notoriously good in building up static electricity and as Lewis Miller says this is what you saw.

I tried waving the blanket underneath the lamp again and the same effect happened.

The blanket was either still charged by the "sweep" or waving it also charged it. Ground the blanket on some metal, (radiator? water line?) and it should behave as your hand if not waved under the lamp (waving might also start the triboelectric effect). Do the experiment with a lamp just turned off, because temperature might play a role in its response to transient fields.

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The phenomenon has to do with the discharge of the static electricity and the resultant RF that is emitted when the arc breaks. the RF emitted from the spark excites the gases inside of the bulb which causes the phosphors to glow. think of the static discharge spark as a teeny tiny lightning bolt.

you can see a similar reaction from the bulb if you were to bring it near a plasma bulb or another source of high frequency electricity like an ignition coil.

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protected by Qmechanic May 25 '17 at 14:58

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