One of the HYPER lab’s favorite demonstrations for visitors is magnetizing air — yes, the stuff you’re breathing can be magnetized. We play around before these demos and come up with amazing ideas, and we’ve got patent-pending technology to prove it.
Here’s what you’ll need to do this:
- Support a small metal container over a surface. In the picture above we’re using a thin-walled stainless steel beaker and a test-tube stand.
- Fill the metal container with liquid nitrogen (make sure you’re following all necessary safety precautions before handling liquid nitrogen).
- Because the normal boiling point temperature of liquid nitrogen (~77 K) is less than the normal boiling point temperature of air (~80 K), liquid air will begin to condense on the outside of the container.
- Use a small pyrex dish to catch the liquid air droplets as the drop off of the metal container.
- Use a neodymium or other strong magnet below the pyrex dish to pull around the liquid air droplets.
Here’s a video:
Here’s an explanation of why this happens:
Liquid oxygen has two unpaired electrons in it’s outer 2p electron orbits. These vacancies give the O2 molecule a net spin, the spin in turn is the movement of electrons, which will interact with a magnetic field. It’s called paramagnetism — unusually magnetic — and only occurs when oxygen is dense, and slow enough, to be significantly influenced by the magnet.
What it does:
For most kids, this is a literal magic trick enabled by science. “WOW!” is all too common. For engineers working in cryogenics, playing like this causes a “what if we put magnets on _____?”!!” moment that can lead to innovation.