Transcript:

So, on this bitterly cold day — it is 3°F — we're going to talk about something that is warm and comforting. We're going to talk about popped corn.

Corn is one of the few grains that pop. And the magic is in the husk. The husk of the kernel of the corn has a special property. It can withstand the exertive force that acts on it. I'll explain what happens.

When a corn is put in the pan and warmed up, the water inside the kernel changes state. It goes from liquid to gas. It becomes steam. Now, steam obeys Boyle's law. What does it mean? It means in a fixed volume, if you heat it up, the pressure will increase. And pressure is an outward force that acts on the husk of the kernel of the corn.

And the husk withstands that pressure up to a point, after which it pops. And that's how you get popped corn. The remainder of the corn which has not popped has a husk that is defective, which is why it burns.

Now you know.