What happens when liquid nitrogen and liquid oxygen are exposed to a strong magnetic field?
Announcer: Frostbite Theater presents... Cold Cuts! No baloney!
Joanna and Steve: Just science!
Joanna: Hi! I'm Joanna!
Steve: And I'm Steve!
Joanna: And this is a test tube of liquid nitrogen!
Steve: And this is a test tube of liquid oxygen!
Joanna: Let's see what happens when we pour the liquids past the poles of a strong magnet!
Joanna: Now, liquid nitrogen isn't normally magnetic, but each of the nitrogen molecules acts like a tiny magnet when it's exposed to a magnetic field. This effect is known as diamagnetism. That's just a fancy way of saying that each of the nitrogen molecules is repelled by the magnet's magnetic field. So, when I pour the liquid nitrogen past the magnet's poles...
...it doesn't look like anything special happens. The nitrogen just falls past the magnet. That's because the diamagnetic effect is very weak, so we don't normally observe it. All materials are at least slightly diamagnetic, but because the effect is so tiny, we don't normally notice it.
Steve: Just like nitrogen, oxygen isn't normally magnetic. And, just like nitrogen, each molecule of oxygen behaves like a tiny magnet when it's exposed to a magnet's magnetic field. Oxygen behaves differently than nitrogen, though. The way oxygen behaves is called paramagnetism. That's a fancy way of saying that each molecule of oxygen is attracted to a magnet's magnetic field. So, when I pour the liquid oxygen between the poles of the magnet...
...it sticks! And we can even make a little bridge out of liquid oxygen that will stay there until the oxygen finally boils away.
Joanna: Thanks for watching! I hope you'll join us again soon for another experiment!
Steve: Let's try that with liquid nitrogen at the same time!
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