WEBVTT - BrainStuff Classics: How Do Microwave Ovens Work?

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<v Speaker 1>Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff.

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<v Speaker 1>Lauren bog Obam here with another classic episode from our

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<v Speaker 1>archives and our previous host, Christian Sager. Today's topic is

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<v Speaker 1>about one of those modern miracles of the kitchen and

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<v Speaker 1>heroes of quick cooking and leftovers alike, the microwave. Hey,

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<v Speaker 1>brain Stuff. This is Christian Sager. There is no denying it.

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<v Speaker 1>Microwave ovens are super convenient. They can heat food much

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<v Speaker 1>more quickly than a conventional oven, although not always with

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<v Speaker 1>the same results. And there's an entire industry of food

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<v Speaker 1>made specifically for these nifty gadgets. But how do they work? Yeah,

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<v Speaker 1>of course you're saying right now, well microwaves. Sure, yeah, microwaves.

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<v Speaker 1>But what the heck are microwaves? Good question, Christian. Microwaves

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<v Speaker 1>are a type of wave on the electro magnetic spectrum,

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<v Speaker 1>and their sandwiched between radio waves and infrared adiation. In

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<v Speaker 1>the case of microwave ovens, the most common wave frequency

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<v Speaker 1>is roughly two thousand, four hundred and fifty mega hurts

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<v Speaker 1>that's about two point four five giga hurts. Waves in

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<v Speaker 1>this frequency range have an interesting property. They're absorbed by water,

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<v Speaker 1>fats and sugars, and once absorbed, they're converted directly into

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<v Speaker 1>atomic motion, which we like to use as heat. These

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<v Speaker 1>waves have another convenient property. They're not absorbed by most plastics, glass,

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<v Speaker 1>or ceramics. Metal, however, does reflect microwaves, which is why

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<v Speaker 1>it's a bad idea to leave a spoon in your

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<v Speaker 1>cheese dip when the ovens on. It's also why the

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<v Speaker 1>devices have metal walls for reflection. You'll often hear people

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<v Speaker 1>say microwave ovens cook from the inside out, right, that's

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<v Speaker 1>the key to the speed. Think about it like this.

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<v Speaker 1>Let's say you're baking a cake in a conventional oven.

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<v Speaker 1>Normally you would bake it at three and fifty degrees

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<v Speaker 1>fahrenheit or a hundred and seventy seven degrees celsius. But

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<v Speaker 1>this time you accidentally set the oven at six hundred

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<v Speaker 1>degrees fahrenheit. The outside of the cake will burn before

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<v Speaker 1>the inside even gets warm, and you'll have ruined somebody's birthday.

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<v Speaker 1>In a conventional oven, the heat has to migrate by

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<v Speaker 1>conduction from the outside of the food toward the middle.

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<v Speaker 1>Hot dry air on the outside evaporates moisture, so the

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<v Speaker 1>outside can be crispy and brown like the crust unbread

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<v Speaker 1>while the inside is moist. In microwave cooking, the radio

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<v Speaker 1>waves penetrate the food and excite water and fat molecules

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<v Speaker 1>more or less evenly throughout. No heat has to migrate

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<v Speaker 1>toward the interior by conduction. There's heat everywhere, all at

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<v Speaker 1>once because the molecules are all excited together. There are

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<v Speaker 1>limits to this, though. Microwaves penetrate unevenly in thick pieces

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<v Speaker 1>of food. They don't make it all the way to

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<v Speaker 1>the middle, and there are also hot spots that are

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<v Speaker 1>caused by wave interfere It's but you get the idea.

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<v Speaker 1>The heating process is different because you are exciting atoms

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<v Speaker 1>rather than conducting heat. Inside a microwave oven, the air

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<v Speaker 1>is at room temperature, so there's no way to form

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<v Speaker 1>a crust. That's why microwavable pastries or hot pockets sometimes

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<v Speaker 1>come with a little sleeve made out of foil and cardboard.

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<v Speaker 1>The sleeve reacts to microwave energy by becoming very hot.

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<v Speaker 1>This exterior heat lets the crust become crispy, as it

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<v Speaker 1>would in a conventional oven. Today's episode was written by

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<v Speaker 1>Ben Bolan and produced by Tyler Klang. Brain Stuff is

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<v Speaker 1>production of I Heart Radio's how Stuff Works. For more

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<v Speaker 1>in this and lots of other quick topics, visit our

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<v Speaker 1>home planet how stuff Works dot com and for more podcasts.

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<v Speaker 1>For my heart radio, visit the heart radio app, Apple Podcasts,

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