Science Questions

How should or why should a polyester sheet make a fluorescent light bulb glow?

Sun, 6th Sep 2009

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Question

Dane Buxbaum asked:

How should or why should a polyester sheet make a fluorescent light bulb glow? I accidentally rubbed my pillowcase, which is 100% polyester against the mini-fluorescent bulb, which is in my bedside lamp. And it glowed for a split second, I repeated this numerous times and every time it worked as long as I touch the contacts. Itís just a simple lamp from Wal-Mart made in China. Am I being exposed to some kind of random chemical or radioactive toxin or something?

Answer

Dave -   No, this is perfectly normal.  In fact we did a Kitchen Science on this a couple of years back.  Basically polyester is a polymer which is quite good at charging up.  So if you rub that against your hair or against other sheets it would tend to, as it touches the sheets it would slowly get electrons transfer to it (or away from it, Iím not sure which way with polyester) and so it gained a charge.  This means if you move it near a fluorescent tube, a fluorescent tube is basically hollow tube with some very low pressure mercury gas in it.  Some of that mercury gas will be ionized, it wouldíve lost electron, you move a charged thing near that some of those ions will move towards or away from the charged thing, will accelerate along, will hit other mercury atoms and knock electrons off those and then youíll get a cascade effect.  And get a little bit of electric current flowing through the tube one way, when you take it away then it will flow back again, and that will transfer energy to the mercury atoms some of that they will release as ultraviolet light.  This will hit the sort of white coating inside of the tube and that will emit visible light, which you can see as this flash of light.

Chris -   So thereís nothing radioactive about your bed, itís okay then, youíre okay.

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BUXBAUM,DANE asked the Naked Scientists: I accidentally rubbed my pillowcase (100% polyester) against the mini fluorescent bulb in my bed side lamp and it glowed for just a split second. I repeated the phenomenon numerous times to even greater effect. It would not work with any other fabric I tried - nor the flesh of my hand. I should say that the lamp was turned off at the time. The bedspread set was purchased at Walmart and made in China. Am I being exposed to some kind of chemical or radio active toxin??? What could have caused this? What do you think? BUXBAUM,DANE , Tue, 3rd Feb 2009

Static electricity anybody? Chemistry4me, Tue, 3rd Feb 2009

Yes, it's static electricity. You can generate very high fields from static electricity (many kV) and these are enough to strike a fluorescent tube. If you take a traditional fluoescent tube and stand under a power line with the tube vertical, you can get it to strike easily. They won't glow very brightly because the current flow is low, but it can be surprisingly bright.

No worries, Dane. graham.d, Wed, 4th Feb 2009

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