1 00:00:02,040 --> 00:00:07,280 Speaker 1: Welcome to brain stuff from how stuff works. Hey, everybody, 2 00:00:07,320 --> 00:00:11,119 Speaker 1: it's me Christian Sager. Now today's question is why is 3 00:00:11,200 --> 00:00:15,640 Speaker 1: it so painful to bite into aluminum foil? And if 4 00:00:15,720 --> 00:00:18,480 Speaker 1: you're from across the pond, you may be wondering right now, 5 00:00:18,760 --> 00:00:22,840 Speaker 1: why is he saying aluminium instead of aluminium? Well, I'm American, 6 00:00:23,160 --> 00:00:25,680 Speaker 1: That's how I pronounced it all my life. I apologize. 7 00:00:25,840 --> 00:00:29,680 Speaker 1: We're gonna go forward with aluminum. But it's a good question, right. 8 00:00:29,880 --> 00:00:33,559 Speaker 1: So first things first, it's actually not painful for everybody 9 00:00:33,600 --> 00:00:36,760 Speaker 1: to bite into this foil. It's painful for people who 10 00:00:36,760 --> 00:00:40,640 Speaker 1: have fillings or crowns made of metal. You probably already 11 00:00:40,680 --> 00:00:44,080 Speaker 1: knew that part, So let's fast forward. What is actually 12 00:00:44,159 --> 00:00:48,040 Speaker 1: happening here. It's sort of like making a battery. So 13 00:00:48,080 --> 00:00:51,920 Speaker 1: how does this happen exactly? Well, first, it's two different metals, 14 00:00:51,960 --> 00:00:55,720 Speaker 1: the aluminum foil and the metal in your filling or crown. 15 00:00:56,280 --> 00:01:00,279 Speaker 1: They have what's called an electrochemical potential difference, and they 16 00:01:00,320 --> 00:01:03,480 Speaker 1: create the sort of voltage in the environment in your mouth, 17 00:01:03,520 --> 00:01:07,080 Speaker 1: which is moist and salty. It's produced by your saliva. 18 00:01:07,440 --> 00:01:10,640 Speaker 1: It's perfect for these two things to come into contact 19 00:01:10,720 --> 00:01:15,560 Speaker 1: this way and to transmit energy. The electrical stimulation from 20 00:01:15,560 --> 00:01:19,160 Speaker 1: this bootleg battery you have created is hitting the nerve 21 00:01:19,480 --> 00:01:23,600 Speaker 1: in your tooth, and that is producing that weird, unique pain. 22 00:01:24,080 --> 00:01:27,399 Speaker 1: The production of this current between the contact of two 23 00:01:27,520 --> 00:01:31,679 Speaker 1: dissimilar metals. It's actually a pretty old concept. It's called 24 00:01:31,959 --> 00:01:37,600 Speaker 1: the voltaic effect. It's named after a guy named Alessandro Volta, 25 00:01:37,640 --> 00:01:40,920 Speaker 1: who most people credit with discovering this. In fact, if 26 00:01:40,959 --> 00:01:43,360 Speaker 1: you want to learn more about this, on my other podcast, 27 00:01:43,400 --> 00:01:46,240 Speaker 1: Stuff to Blow Your Mind, we went really far into 28 00:01:46,319 --> 00:01:50,520 Speaker 1: voltaic batteries in an episode we did on Frankenstein. Now 29 00:01:50,600 --> 00:01:54,320 Speaker 1: Volta he was making extra batteries a long time ago, 30 00:01:54,560 --> 00:01:57,320 Speaker 1: and what he did was he stacked these dissimilar metals 31 00:01:57,360 --> 00:02:00,160 Speaker 1: together and in between them he would put water her 32 00:02:00,240 --> 00:02:03,840 Speaker 1: paper soaked with salt water. And he found that by 33 00:02:03,880 --> 00:02:07,960 Speaker 1: doing this he could create a very low power battery. 34 00:02:08,400 --> 00:02:11,840 Speaker 1: So that's essentially it. That's what's happening when you open 35 00:02:11,919 --> 00:02:14,000 Speaker 1: a candy bar and you bite down on a piece 36 00:02:14,040 --> 00:02:16,640 Speaker 1: of chocolate that still has a little bit of foil 37 00:02:16,720 --> 00:02:19,600 Speaker 1: in it and you freak out because it's painful. You're 38 00:02:19,680 --> 00:02:28,760 Speaker 1: essentially creating a battery in your mouth. Check out the 39 00:02:28,760 --> 00:02:31,120 Speaker 1: Brainstuff channel on YouTube, and for more on this and 40 00:02:31,160 --> 00:02:45,880 Speaker 1: thousands of other topics, visit how stuff works dot com.