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Ever Wonder About Static Electricity?

I have a sweater that snaps, crackles and pops when I take it off. That might be why it was on sale, though probably it had more to do with an imbalance of electrical charges than a balance of credit card charges.

The spark occurs when a difference in charge between me and my sweater is so great (around 6000 volts!?) that electrons jump through the air between them. This action heats up the air molecules so much they turn to plasma, giving off light and sound—a mini lightning and thunder show. This could be a problem at a gas pump, but the current is not great enough to turn me into charred lump.

My acrylic sweater, like many synthetic materials, is an insulator—it tends to hang on to electrons. Electrons are negatively charged and so materials with an excess of them, become negative. I, like many biological materials, am more of a conductor and able to transfer electrons easily. 

Moisture in the air transfers away extra electrons. In the winter, however, the air in my house gets warmed up and dried out. So the electrons build up a negative charge in my sweater. The electrons in my skin are repelled so the positive ions are near the surface and are attracted to the sweater. When I pull the sweater off, electrons jump.

Rubbing materials together allows for more surface area to come into contact and transfer more electrons. Materials can be arranged in a triboelectric series, from those more likely to collect electrons toward the bottom to materials more likely to lose electrons toward the top. The further apart two materials are in the series, the more easily electrons will pass between them. As I move around during the course of the day, my sweater rubs against me and picks up electrons.

The shocking thing is that materials do not simply become positive or negative. If two of the same kind of material (pieces of paper) are rubbed together, each piece develops a mosaic of areas with positive charge and areas of negative charge. They stick together where the positive areas of one are near the negative areas of the other. So it seems that current explanations about electricity are not static.

Even if I am not sure about the theory, I can look for solutions to the problem of getting zapped by my sweater. Some sprays can make insulating materials more conductive but they can be unpleasant for various reasons. An interesting suggestion was to attach safety pins to my sweater to help conduct away the electrons. So far, it seems to crackle but I haven't actually been zapped. So, I can't be too negative about the idea even though I'm not positive it works.


You might also like this video, where we present some free, electricity activities you can try out at home!