1 00:00:02,040 --> 00:00:06,960 Speaker 1: Welcome to brain Stuff from how Stuff Works. Hey, brain 2 00:00:07,040 --> 00:00:09,240 Speaker 1: stuff is Christian Saker here. When you were a kid, 3 00:00:09,280 --> 00:00:12,280 Speaker 1: did you ever rub a balloon really fast against your 4 00:00:12,320 --> 00:00:16,000 Speaker 1: hair to make it stick? What about as an adult? Well, 5 00:00:16,040 --> 00:00:21,040 Speaker 1: after many years of speculation, Case Western Reserve University scientists 6 00:00:21,040 --> 00:00:26,040 Speaker 1: have pinpointed exactly why this party trick happens. We've known 7 00:00:26,079 --> 00:00:29,400 Speaker 1: forever that when two objects are rubbed against each other, 8 00:00:29,480 --> 00:00:32,640 Speaker 1: there's a build up of an electrical charge called static 9 00:00:32,680 --> 00:00:37,600 Speaker 1: electricity or tribo electric charging. If the two objects have 10 00:00:37,760 --> 00:00:42,440 Speaker 1: opposite charges, positive and negative, they'll stick together. But some 11 00:00:42,640 --> 00:00:46,680 Speaker 1: objects appear to charge more or stick more closely together 12 00:00:47,000 --> 00:00:50,520 Speaker 1: than others, like the balloon on your hair. Now, why 13 00:00:50,600 --> 00:00:53,519 Speaker 1: is that? According to a new study published in the 14 00:00:53,640 --> 00:00:57,760 Speaker 1: journal Physical Review Materials, the crux of the phenomenon lies 15 00:00:58,120 --> 00:01:01,880 Speaker 1: and how strained the balloon material is. For the purpose 16 00:01:01,960 --> 00:01:07,560 Speaker 1: of this study, the scientists stretched a film of polytetrafluoro ethylene. 17 00:01:07,800 --> 00:01:10,840 Speaker 1: Let's just call it PTFE for now. That's one of 18 00:01:10,880 --> 00:01:13,800 Speaker 1: the brand names for teflon. They took that and they 19 00:01:13,880 --> 00:01:18,760 Speaker 1: rubbed it against a film of unstrained, unstretched ptf E, 20 00:01:19,200 --> 00:01:22,480 Speaker 1: and they found that even though the materials were chemically identical. 21 00:01:22,800 --> 00:01:26,920 Speaker 1: They generated charge transfer in one direction as if they 22 00:01:26,959 --> 00:01:31,600 Speaker 1: had two different chemical compositions. The stretched or strange sheet 23 00:01:31,680 --> 00:01:35,200 Speaker 1: carried the positive charge, while the unstrained sheet carried a 24 00:01:35,360 --> 00:01:39,440 Speaker 1: negative charge. The more strained the material was, the more 25 00:01:39,480 --> 00:01:43,920 Speaker 1: likely it was to experience systematic charge transfer. This is 26 00:01:43,959 --> 00:01:47,840 Speaker 1: because the micro structure of the material was altered when strained, 27 00:01:48,000 --> 00:01:52,880 Speaker 1: leading to tiny holes and cracks. These imperfections allowed the 28 00:01:52,960 --> 00:01:59,280 Speaker 1: rubbing induced friction to facilitate charge transfer, leading to static electricity. 29 00:01:59,560 --> 00:02:02,760 Speaker 1: In a pre US release, co authored Dan Lax explained 30 00:02:02,960 --> 00:02:05,960 Speaker 1: that they think the void regions in the fibrils these 31 00:02:06,000 --> 00:02:09,960 Speaker 1: are tiny cell fibers. They think that those were strained 32 00:02:10,200 --> 00:02:14,320 Speaker 1: when the polymer had different bonding and thus a charge 33 00:02:14,440 --> 00:02:18,120 Speaker 1: that was different. The researchers also examined the phenomenon using 34 00:02:18,160 --> 00:02:21,440 Speaker 1: packing peanuts, which just love to stick to people's arms. 35 00:02:21,440 --> 00:02:25,440 Speaker 1: In fact, polystyrene peanuts and plastic bags are currently being 36 00:02:25,480 --> 00:02:30,799 Speaker 1: closely examined to give us a better understanding of static electricity. Ideally, 37 00:02:31,120 --> 00:02:34,120 Speaker 1: scientists will nail it down so precisely that they will 38 00:02:34,160 --> 00:02:38,360 Speaker 1: be able to control it, helping to prevent tribe electric explosions, 39 00:02:38,400 --> 00:02:41,919 Speaker 1: such as explosions of coal dust in minds and develop 40 00:02:42,200 --> 00:02:46,240 Speaker 1: more effective products, for example, pesticides that will stick better 41 00:02:46,320 --> 00:02:49,560 Speaker 1: to plants or paints that will stick better to cars. 42 00:02:50,000 --> 00:02:53,440 Speaker 1: It may not seem that dangerous, but in fact static 43 00:02:53,480 --> 00:02:58,040 Speaker 1: electricity can ignite fuel vapors at the gas pump, causing fire. 44 00:02:58,360 --> 00:03:01,880 Speaker 1: To avoid such a catastropheure try not to get back 45 00:03:02,000 --> 00:03:05,560 Speaker 1: in the car after you start the fueling process, because 46 00:03:05,600 --> 00:03:10,000 Speaker 1: sliding across the seat generates static electricity. If you must 47 00:03:10,080 --> 00:03:13,640 Speaker 1: re enter your vehicle, be sure to ground yourself first 48 00:03:13,720 --> 00:03:17,040 Speaker 1: when you get back out by touching the metal part 49 00:03:17,200 --> 00:03:26,720 Speaker 1: of your car door. Today's episode was written by Aliya Hoyt, 50 00:03:26,760 --> 00:03:29,480 Speaker 1: produced by Tristan McNeil, and For more on this and 51 00:03:29,560 --> 00:03:44,240 Speaker 1: other topics, please visit us at how stuff works dot com.