Speaker 1: Welcome to Brainstuff, a production of I Heart Radio. Hey
Speaker 1: brain Stuff, I'm Lauren Vogelbaum, and today's episode is a
Speaker 1: classic from our former host, Christian Sagar. This one concerns
Speaker 1: a strange bit of everyday science. Why can it be
Speaker 1: strangely painful to bite down on a piece of aluminum foil? Hey, everybody,
Speaker 1: it's me Christian Sager. Now today's question is why is
Speaker 1: it so painful to bite into aluminum foil? And if
Speaker 1: you're from across the pond, you may be wondering right now,
Speaker 1: why is he saying aluminum instead of aluminium? Well, I'm American,
Speaker 1: That's how I've pronounced it all my life. I apologize,
Speaker 1: we're gonna go forward with aluminum. But it's a good question, right.
Speaker 1: So first things first, it's actually not painful for everybody
Speaker 1: to bite into this foil. It's painful for people who
Speaker 1: have fillings or crowns made of metal. You probably already
Speaker 1: knew that part, So let's fast forward. What is actually
Speaker 1: happening here. It's sort of like making a battery. So
Speaker 1: how does this happen exactly? Well, first, it's two different metals,
Speaker 1: the aluminum foil and the metal in your filling or crown.
Speaker 1: They have what's called an electrochemical potential difference, and they
Speaker 1: create the sort of voltage in the environment in your mouth,
Speaker 1: which is moist and salty. It's produced by your saliva.
Speaker 1: It's perfect for these two things to come into contact
Speaker 1: this way and to transmit energy. The electrical stimulation from
Speaker 1: this bootleg battery you have created is hitting the nerve
Speaker 1: in your tooth, and that is producing that weird unique pain.
Speaker 1: The production of this current between the contact of two
Speaker 1: dissimilar metals. It's actually a pretty old concept. It's called
Speaker 1: the voltaic effect. It's named after a guy named Alessandro Volta,
Speaker 1: who most people credit with discovering this. In fact, if
Speaker 1: you want to learn more about this, on my other podcast,
Speaker 1: Stuff to Blow Your Mind, we went really far into
Speaker 1: voltaic batteries in an episode we did on Frankenstein. Now
Speaker 1: Volta he was making extra batteries a long time ago,
Speaker 1: and what he did was he stacked these dissimilar metals
Speaker 1: together and in between them he would put water paper
Speaker 1: soaked with salt water. And he found that by doing
Speaker 1: this he could create a very low power battery. So
Speaker 1: that's essentially it. That's what's happening when you open a
Speaker 1: candy bar and you bite down on a piece of
Speaker 1: chocolate that still has a little bit of foil in it,
Speaker 1: and you freak out because it's painful. You're essentially creating
Speaker 1: a battery in your mouth. Today's soote was written by
Speaker 1: Ben Bollen and produced by Tyler Clang. For more on
Speaker 1: this and lots of other topics, visit how stuffworks dot com.
Speaker 1: Brain Stuff is a production of I Heart Radio. For
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