WEBVTT - How Do Car Horns Work?

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<v Speaker 1>Hi. I am Tracy V. Wilson and I'm Holly Fry.

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<v Speaker 1>We are the co hosts of the Stuff You Missed

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<v Speaker 1>in History Class podcast from how Stuff Works dot com.

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<v Speaker 1>And as you might suspect from the name, what we

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<v Speaker 1>like to talk about are the things that are of

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<v Speaker 1>historical significance but maybe you didn't hear about in your

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<v Speaker 1>standard history class. So sometimes they are famous figures and

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<v Speaker 1>we're talking about the lesser known parts of their lives.

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<v Speaker 1>Sometimes they are people in groups and places that are

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<v Speaker 1>often overlooked in history class. Lots of cool stuff, so

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<v Speaker 1>come and join us. Hey, everybody, this is Christian Seger.

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<v Speaker 1>Welcome to brain Stuff from How Stuff Works. My name

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<v Speaker 1>is Christian, My world is fire and blood. Once I

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<v Speaker 1>hunked the horn of my interceptive Pursuit special, it's hard

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<v Speaker 1>to know who was more crazy, me or everyone else. No, really,

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<v Speaker 1>when people haunt car horns, they're pretty freaking aggressive. Research

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<v Speaker 1>shows were more likely to do it when it's hot outside,

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<v Speaker 1>when it's a week day, and if you're male, that's right.

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<v Speaker 1>War boys here in the US, your run of the

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<v Speaker 1>mill car horn is a hundred and ten decibels of

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<v Speaker 1>sustained noise. While the vehicle horns of yesteryear had different

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<v Speaker 1>combinations of notes, today they're mostly regulated to sound the same,

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<v Speaker 1>and the law requires you to have a car horn

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<v Speaker 1>if they're so important. Let's talk about how car horns work.

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<v Speaker 1>Typical car horns these days are electro mechanical. There are

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<v Speaker 1>two horns per vehicle, usually each sounding at a different

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<v Speaker 1>pitch to produce a cord. These horns generally consist of

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<v Speaker 1>a spring, steel diaphragm, a coiled wire, a switch, and

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<v Speaker 1>housing that amplifies sound like a megaphone. All of this

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<v Speaker 1>is mounted somewhere behind your vehicle's grill. So when you

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<v Speaker 1>slam your hand on that steering wheel button with a

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<v Speaker 1>little trumpet symbol on it, it sends an electrical current

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<v Speaker 1>through a relay and onto a copper coil that supplies

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<v Speaker 1>electricity to the horn. To create such a loud sound

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<v Speaker 1>takes a lot of energy. In fact, the only accessory

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<v Speaker 1>that uses more juice in your car is the starter.

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<v Speaker 1>The electrical current surging into the horn creates a magnetic field.

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<v Speaker 1>This field causes the flat circular diaphragm inside to oscillate.

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<v Speaker 1>The oscillation is set up by the diaphragm flexing to

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<v Speaker 1>its mechanical limit and then releasing back past its neutral position,

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<v Speaker 1>only to be pulled forward again. This functions by using

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<v Speaker 1>the basic law of elasticity, also known as Hook's law

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<v Speaker 1>because it was formulated in the seventeenth century by an

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<v Speaker 1>English scientist named Robert Hook. The law states that the

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<v Speaker 1>strain of a body is proportional to the stress applied

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<v Speaker 1>to the body. What this means for the car horn

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<v Speaker 1>is that it's diaphragm will oscillate continuously as long as

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<v Speaker 1>the current is applied. There are also other types of

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<v Speaker 1>horns used in vehicles, air horns, Clason's whistles similar to

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<v Speaker 1>organ pipes, and even sirens like we see on emergency vehicles,

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<v Speaker 1>but the electro magnetic car horn is the most common one.

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<v Speaker 1>You're going to find out there in the waste land.

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<v Speaker 1>Now that you're armed with this knowledge, you should be

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<v Speaker 1>ready to grab the sun and ride into Valhalla. Check

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<v Speaker 1>out the brain stuff channel on YouTube, and for more

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<v Speaker 1>on this and thousands of other topics, visit how stuff

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<v Speaker 1>works dot com.