How to float a frog in a magnetic field.

Some who read this (if anyone actually reads this blog) will probably thing there are a lot of things wrong with the title of this post. First of all, in high school you probably have learned that only other magnets or metallic objects (containing iron, nickel or cobalt) are attracted to magnets. Frogs aren’t metallic (aside from the traces of iron in a frogs blood) nor are they magnetic. Secondly, if you’ve ever tried to take two magnets, put one on the ground and try to float the other above the first using magnetic repulsion, you know this is impossible. So floating a frog in a magnetic field seems very unlikely. No, not unlikely, unphysical!

Well, if it weren’t for quantum mechanics, it would be unphysical. I assure you, however, floating a frog is very possible and has been done! A small group in Norway used an incredibly powerful magnet to float a frog. Not only a frog, but water, a strawberry and a grasshopper! Here’s the link to their site which has videos.

So, how did they do it? Firstly, you need to know a bit of electromagnetic theory. Specifically the fact that moving charges create magnetic fields. For example, if you run a current through a wire, you are sending billions of electrons through it per second. This actually causes a small magnetic field around the wire which you can “see” by putting a compass next to it.

Next you need to know that atoms, the building blocks of matter, are made of a positively charged nucleus and negatively charged electrons which orbit around it. That’s right, moving electrons means moving charge, which means a magnetic field associated with every atom. The atoms in materials called diamagnetic materials (like water, carbon, graphite…) have a strange property which makes their atomic magnetic poles oppose the magnetic pole of a nearby magnet. What I mean by this is that if you put a diamagnetic material, like water, near the north pole of a magnet, the water atoms will line up so that their north poles point towards the magnet. The north poles of the atoms and the magnet will then push each other away, so, theoretically, the water will repel the magnet.

In reality effect is so small that it counts for almost nothing. It’s probably pointless to get your heavy duty magnet and try it out. It won’t work. If you are a physicist, however, with a magnet 200 times stronger than a regular store-bought magnet, the effect is noticeable, very noticeable, and you can actually get a frog (maybe even a person) to float in mid air.